People really struggle with the concept of casual racism, like if the person isn't physically attacking a minority or marching with a torch, then they insist it's mere ignorance or insensitivity. Those are all parts of racism! Shit, MOST racism stems from that - people going out of their way to not give a shit.
So, sure, he probably did just pick up that word from toxic gaming culture years ago, but that's also racism - casually throwing the word around as an edgy insult or whatever. It all falls under the same umbrella.
Some people just have a super narrow idea of what qualifies, and I think there's a reason for it.