The one that you describe where the co-workers are being nice and the black guy is being an asshole for complaining about it.

Alternatively, this guy could be simply misinterpreting a pretty (all things considered) passable gesture. As I mentioned before: hanlons razor.

Or the other scenario where the black dude's co-workers are making assumptions about the dude ....

Totally plausible. This is an office party- we only know so much.

...based on stereotypes.

Why this? Yeah people can be insensitive but that's a hell of a leap to make here.

In which case the black dude is rightfully bothered by this and the co-workers are making ignorant assumptions based on race.

Possible? Sure. Here's my take: I just got cake and free booze. How we choose to interpret things goes a long way. Even if it were racially driven- there's two sides of this... and only of them is backed by malice... and if so: as I mentioned ... that's a big spend to be a dick.

If he wants to be offended by all means: go to hr. But he posted it on Twitter. Excuse me for being blunt but based on where he posted it- he was looking for a reaction and won't further speculate there.

And I see you making further ignorant ...

I mentioned earlier that a lot of things have to do with perception. You are running to defend a dubious at best situation with minimal information. You have no skin in this- there is no reason to be so invested in something where you would attribute my blunt, but fair, assessment as malice. Many people would do well to take a breath before jumping to conclusions... we'd all be better for it.

We can't know which scenario is true.

You should have stopped there.

Try to be a better person.

Every day. How about you?