At least by his own recollection. Anyone who is harboring that kind of hostility, whatever the cause, is going to exude pretty strange vibes in person.
What's disturbing to me is not that an obviously talented young person like the OP has these kinds of issues. He'll almost certainly grow out of them.
It's that so many older, wiser people, who obviously don't have personal problems of their own, seem intent on encouraging this way of thinking. Just because you think you're doing good, doesn't mean you actually are.
So are you saying that "strange vibes" should be a firing offense in an office run like the one the author describes? If not, what are you getting at? To me, it sounds like the author regularly has to deal with discrimination being both black and gay. Some will respond to this with indifference, others bravado. There is nothing immature, as you imply, about a bitter and withdrawn response to this. To claim that he is some innately hostile person ("harboring that kind of hostility") says an awful lot about how you reason about power dynamics.
This is the strangest part of your claims. I don't see anything indicating that he's a remotely competent worker. Admittedly, I haven't researched who he is, but the only credibility he's got is that he can set up a Tumblr and add pictures to his post. I am not impressed at his technical skill–or his grammar, spelling, diction, or eloquence–indeed nothing about him says he's worth my time except that he's human and hurting.
If anything, this offhand remark of yours serves to undermine your credibility to me.