I think you are confusing a political campaigning organization with a social club.

LGB Alliance was not started, nor does it aim, to foster social connections amongst same-sex attracted people. It's not a place, nor does it plan to set up a place IRL or online, where people who are L, G and B can get together and make friends, hang out, chat, share ideas, hold hands, have parties, figure out your identity, get validation, acquire a sense of belonging, etc. Its purpose is to advance the interests and protect the rights of same-sex attracted people. It's not like a gay & lesbian alliance at school; an LGBTQ community center; or a gay or lesbian bar. From the LGB Alliance website:

Our Mission

To advance lesbian, gay and bisexual rights

We advance the interests of lesbians, gay men and bisexuals, and stand up for our right to live as same-sex attracted people without discrimination or disadvantage. We will ensure that the voices of lesbians, gay men and bisexuals are heard in all public and political discussions affecting our lives.

To highlight the dual discrimination faced by lesbians

We amplify the voices of lesbians and highlight the dual discrimination experienced by lesbians as women who are same-sex attracted in a male-dominated society.

To protect children who may grow up to be lesbian, gay, or bisexual

We work to protect children from harmful, unscientific ideologies that may lead them to believe either their personality or their body is in need of changing. Any child growing up to be lesbian, gay or bisexual has the right to be happy and confident about their sexuality and who they are.

To promote free speech on lesbian, gay and bisexual issues

We promote freedom of speech and informed dialogue on issues concerning the rights of lesbians, gay men and bisexuals. We assert that different opinions, even those we may disagree with, should be heard as part of the public debate.

---

I think the LGB Alliance would be more effective if they concentrated on excluding straight people

See, this is the problem with identity politics. Many straight people have the skills, expertise, professional qualifications to help the LGB Alliance meet its aims. A person doesn't have to be gay, lesbian or bisexual to be committed to gay, lesbian and bisexual rights, equality, acceptance, health, wellbeing, etc. Many people who are straight have worked effectively in the public, political, legal and health care spheres, etc. advancing the interests of same-sex attracted people over time.

I am not a gay man. But I worked with organizations such as Gay Men's Health Crisis and ACT UP during the AIDS crisis in the 1980s and 90s to advance the interests of gay men and other MSM/MLM with HIV-AIDS and at high risk of it. I and many other women contributed a wide range of skills, insights, knowledge and life experience that were very much needed and which were valuable to the cause and which helped these groups of men. I sometimes even spoke to the press and went on TV to speak about AIDS and HIV and the suffering discrimination it caused.

I also used to work for a Jewish charity for newly arrived refugees in NYC that was originally founded by the Hebrew Immigrant Aid Society to help resettled Holocaust survivors in the USA, but I am not Jewish, not an immigrant or a refugee. The people I worked under were nearly all Jewish Holocaust survivors from Eastern Europe, but they hired me a goy from the USA who grew up going to Roman Catholic convent school, and who had never been a displaced person or witnessed warfare and genocide firsthand, because they thought I had skills and talents I could offer. (And they liked my personality.)

In the 1970s, one of my sisters was executive director of an organization to promote the interests of Soviet Jews, but she was not Jewish or from the Soviet Union. She was an expert in international human rights, and a powerful advocate in Washington DC and on the world stage for various groups that she did not personally belong to - among them, dissidents in Chile, political prisoners around the world, religious and ethnicity minority groups whose countries/lands had been taken over by hostile forces and who had been forced into exile, women in "the third world," and LGBT people in places like Pakistan, Iran and Jamaica. The fact that she was not a member of those groups did not mean she was not an effective advocate for their interests.

Campaign groups working for civil rights whose aim is to bring about social, legal and political change and to gain greater understanding and acceptance for marginalized populations are shooting themselves in the foot if they only take persons who belong to a certain group.

I really despair of all this identity bullshit that's so entirely focused on deciding who belongs in the group and who is an outsider, and which constantly fosters the mistaken notion that the only people who can contribute to advancing the interests of X, Y, Z group are those inside that group who have A, B, C characteristics and can tick off D, E, F boxes.

Of course outsiders should not lead advocacy efforts for marginalized groups - but outsiders can contribute in myriad ways, and outsiders can be just as sincere and devoted in their commitment to "the cause" as some insiders can.

On the issue of "the LGB" and the T, I know plenty of gay men, lesbians, bisexuals and people who identify as trans who have done nothing, diddly squat, to advance the interests of same-sex attracted people and/or trans-identified people. At the same time, I know plenty of straight people who have done quite a bit for these groups and for acceptance of nonconformists and minorities in general.

---

ETA: the LGB Alliance does not have a membership and does not give out membership cards. Because it's not an org that people join like they do a social club, political party, union, sports league, civic association or fan club; and it's not in the business of providing membership cards or documents that people can use as a badge proving that they belong and will gain them entry into special places and events, provide evidence of their "identity," or enable them to obtain services like taking out a library book or getting a discount when paying for purchases.

LGB Alliance has a staff of unpaid volunteers who run it. It also has supporters and financial contributors. If you click the "Join" tab on the website, a form comes up that says "Join our Supporter mailing list." The "Donate" tab gives an option to give money on a one-time or recurring basis. Donors can click an option to have their contribution listed as coming from "Friends of the LGB."

Anyone can register as a supporter, donor, friend of the LGB Alliance. People don't have to be same-sex attracted to register for the mailing lists, donate money or be listed as a financial contributor who counts as a Friend of the LGB Alliance.