"Multiracial Whiteness" sounds like one of those terms made up by sociology professors with too much time on their hands.

yeah but is that really what they're talking about here?

i think it's clear from the image they used they want to try and classify people as "multiracially white" so that they can attack them the same way they do with actual Whites, without being called racist.

I mean that is the leader of the proud boys after all.