I have no idea if that is true or not, but it is irrelevant because it is quite possible for black people to be racist and also to take part in anti-black racism.
I'll note that my comment did not directly link proud boys to "white supremacy". Instead, I (and the comment I replied to) used "right-wing extremists". I think that's an accurate description that does not require an assumption that "Western = white".
For anyone curious about their beliefs:
https://proudboysusa.com/tenets/
Minimal Government
Maximum Freedom
Anti-Political Correctness
Anti-Drug War
Closed Borders
Anti-Racial Guilt
Anti-Racism
Pro-Free Speech (1st Amendment)
Pro-Gun Rights (2nd Amendment)
Glorifying the Entrepreneur
Venerating the Housewife
Reinstating a Spirit of Western Chauvinism