The problem with that take is that most immigrants won't/don't join the military. When I was in the Army, sure, I met immigrants who served honorably, but thinking back on it, 1-African, 1-Irishman, 1-South African, 1-Chinese (nice guy, pretty sure he was a spy), 1-Russian and a couple of South Americans (both Chilean) isn't exactly a huge number of immigrants. More Hispanics and Asians were in the Army than any other ethnic group but most of them were 1st gen American, with the majority being Mexican/Central American of that group. I did know of 1-Afghan interpreter that managed to get to the States and join the military. Syrian=0. Almost all the Asians were born in the US, unless they were Pilipino. Granted those were the ones I met personally and became friends with so by no means a huge sampling. But thinking back on it, the % of immigrants who serve isn't a large number compared to the number who cross the border into the U.S. Even among American ethnic groups, the numbers were extremely low. 1-Lakota Sioux, 0=Eskimo, 2-Hawaiian.

You can't draft an immigrant. They have to choose to serve and immigrants aren't exactly lining up. Indians=Not a single one. Indians do not join the American military--period--1st, 2nd or 10th gen. They feel zero obligation to serve the country they moved to or they were born in. Yes, this offends me a little. There are a lot of Indians in the US. You'd think at least a small % would want to serve their country but they simply don't. (I looked up, why don't Indians join the military and it took me to a page full of articles about native Americans which was not what I was asking at all. I would love to have an answer to this question).

Its a good theory, but it doesn't play out in RL on the ground. The majority of immigrants want all the perks of living in the U.S but they aren't going to fight for you, or anyone else. If they were, they would stay in, and fight for, their own country. The fact that they didn't is indicative of their nature.