He has clearly been making an effort to reach out or at least have the appearance that he is reaching out to black people in spaces that Democrats don't.
We've been seeing this from Trump. That's why he had been making an emphasis that he will be appearing at the event and Harris wanted to appear remotely due to scheduling.
His efforts to "reach out" included being in spaces with black rappers, that's a far cry from volunteering to a Q/A at a damn NABJ convention.
They've been inviting him every year since 2016, he could have easily skipped this one too