It's playful banter. The interviewer starts it with "you can't do that to Black Media" jokingly when he needs to leave, and his response is pointing out the obvious. The kind of Black people consuming Black Media aren't going to be voting for Trump, so it'll be ok that he has to leave. Biden isn't a great public speaker. He didn't word this one well. It wasn't a prepared statement, it was a response to other playfuyl banter. It's primarily been used against him by right wing media in false outrage.

I can't be bothered to care about playful banter. He's not redirecting government resources or ignoring folks that didn't vote for him like the last administration. The context above makes it clear what he meant too.

No, the person's intent matters entirely. It's the same issue with comedians making jokes. Some get a pass and some don't. It's all about knowing the person's actual feelings, intent, and historical actions. Dave Chapelle and Kevin Hart received significant pushback from their statements on Trans and Gay people respectively because neither had shown to support either group prior to saying them. Hart, to his credit, has eventually learned why his statements were hurtful and has corrected his behavior (Side note the docuseries on Netflix? i think is pretty great. It covers part of this where he is extremely bullheaded about needing to apologize and how going on Ellen should have been enough, and members of his staff do show him why he's wrong. Overall the series is sort of tragic as his motives are at odds with his family and I came away feeling sad for him more than anything).

If Biden is racist, he's not showing it in any meaningful way today. Republicans don't get the benefit of doubt because their policies are already anti-black. You may want to judge everything separately, but that's not how it works. If someone does or says 9 racists things, it's safe to assume the 10th thing is racist too.