This is such a sampling bias on two counts:

1. The media landscape is dominated by white people, men, and the combination of the two. Part of that is reflective of the baseline demographics - America is the cultural powerhouse of media in the west, most Americans are white, ergo most media figureheads are going to be white. Throw in a big helping of white supremacy and misogyny into the mix and whaddayaknow? It starts skewing even more towards white men.

2. White (cis) men are gonna be more inclined to demand that Biden step down because, paradoxically, they still feel more represented by the Democratic party than a trans person of colour would since the latter is going to be have a much better chance of realising that the Dems don't give a fuck about them, that they aren't going to listen to them anyway, and because of this that person is going to be much more inclined to show interest in radical politics.

To call for Biden to be replaced is to express a personal investment in the Democratic party and to want them to improve.

Personally, I want Biden to stay. I want to see him elected, not because I believe in him or out of some misguided notion of harm-reduction, but because I absolutely do not have any faith in him and I think that a second Biden term would be catastrophic for the libs and it would push more liberals to radicalise.

This tweet is very smug and self-satisfied. They've managed to identify that the US is deeply misogynistic and white supremacist but instead of talking about that they are invoking these notions to silence the people who they disagree with rather than addressing the core of the issue so it's tokenistic af. This argument has the same energy as the "socialism is all old white men" or the "telling people to read theory is ableist" canards - these things aren't being invoked out of any genuine concern for these issues, they're just playing these issues as a gotcha to "win".