Couple of things to mention on this one.
1) You might be forgiven for forgetting that Wallace is in a band and a soccer team. I've mentioned it in the forum once, but never anywhere else, I think... his band is called "Too Funk". (The rarely used full name, of course, is "Too Funk To Druck".)
2) I've said it before and I'll say it again - in much the same way that currently trending Islamophobia is primarily anti-Arab racism, I feel that the current flavour of anti-black racism is actually economic classism. The ostensible fears of anti-black racists - crime, narcotic abuse, aggression, low intelligence - correlate far more strongly with low income than they do with melanin. Blackness just happens to correlate with that, and is more visible and easily stereotypable.
3) Wallace is quite right when he says "if I don't maintain my identity, who's going to do it for me?". If some random commenter mislabels me, it's no one's responsibility but mine to correct them - and, in cases where it might be necessary, to provide proof. The black identity, in particular, is subject to pretenders (a certain infamous Miss Dolezal immediately comes to mind). It raises the question, though, of whether or not Wallace's aborted selfie would have sufficed. Surely, there is more to the black identity than a low epidermal albedo, and proving the entirety of it on a forum post may not even be possible.
4) Anti-black racists love to bring up the concept of selective slave breeding to excuse the disproportionate success of a supposedly inferior race in the meritocracy of professional sports - and then turn around and claim that that same breeding process brought about low intelligence. (Personally, if I were doing selective breeding on my human slaves, I'd be aiming for subservient demeanour rather than stupidity, but what do I know?) Of course, breeding doesn't work that way, especially not in such a short timeframe - you can't breed for lack of intelligence, especially when the species you're breeding is capable of outsmarting you - but what you can do is foster a culture in which overt displays of intelligence are discouraged. Which is to say - all the black friends I've ever had, quite frankly, have been straight-up smarter than me, but I believe there's no other ethnicity/culture on the planet that's better at pretending to be idiots.
5) I believe "finna" is actually meant to be a contraction of "fixing to". "Going to" : "Gonna :: "Fixing to" : "Finna". I could be wrong.