This is true if you think "white supremacy" means "the belief, theory, or doctrine that white people are inherently superior to people from all other racial and ethnic groups, especially Black people, and are therefore rightfully the dominant group in any society," as it says in the dictionary.

In actual practice in the media, though, "white supremacy" means "the belief, theory or doctrine that white people deserve to exist and stand up for their own interests, and explicit discrimination and hatred toward whites should be discouraged." By this definition, the above imgur album is clearly "white supremacy".

The reason that the left has come to term such reasonable beliefs as "white supremacy" is because they have essentially figured out that the right was correct - in a fair, meritocratic, Western system, it's highly probable that blacks and other minority groups will do poorly. Rather than accept, though, that groups have different average abilities, the left decides the entire of society has to be rebuilt in a way that guarantees equal outcomes, which necessitates discriminating against whites. Anyone who opposes this clearly accepts to some degree the status quo, which is why standing up for white people is "white supremacy."

Now for a lot of classical liberals / centrists, this situation is confusing. It seems much like the "soft bigotry of low expectations" to expect blacks and other minorities to do poorly. Surely they must be the real racists! But to a leftist, as well as anyone willing to investigate uncomfortable facts, it's pretty dang obvious that we can expect blacks to score poorly on IQ tests, not show up to work on time, commit violent crime more often and so on. From the leftists' perspective, the view that all races are equal is purposely ignorant and self-serving. The real racism, in their view, is the very belief that high IQ, showing up to work on time, and not committing violent crime are positive traits in the first place. Hence they advocate for abolishing standardized tests, allowing flexible working hours, and freeing violent criminals from jail.

The reality is that we have to accept that groups are different and that we must expect whites to do better than blacks (on average) in the absence of discrimination. It's not enough to have blind faith in liberalism to "bring us equality," we have to accept that inequality between races is the natural (and desirable) result of a meritocratic system. Until we recognize that the anti-white left's observations about the under-performance of minority groups are not "racism", but a simple observation of fact (coupled with anti-white hatred and a misdiagnosis of the cause), we'll never defeat them.