>>105404096hard proof? not much, but there's a good couple of signs
the insult has pretty low overall occurence compared to the more organic one used on the board (only around 1.5k uses compared to the over 8.5k of the other one), but it has relatively high regularity and tends to crop up around same type of threads, showing habitual usage
combine with the fact that the person posted is a massive blacked porn enthusiast and the user of the insult tried to push the black fetish on Mori (rather than fetishes more associated with her) and it's a decent match