Which is 100% likely the case. Even if he was a racist he wouldn't actually knowingly tweet that because it would harm his election chances.
Did you see his Tulsa rally? He has been playing to his base for months now, and that group of ignorant racists is getting smaller and smaller. What you think is a bad move he sees as shoring up support.
"In a field where an overlooked bug could cost millions, you want people who will speak their minds, even if they’re sometimes obnoxious about it."