Just look at it like this, yes some Black people have racist ideas/thoughts etc. that are of a prejudiced and bigoted nature, but you need political and economic power to have supremacy of any kind. Therefore, yes, dude is a Black supremacist in his thinking and wanting to execute his agenda, but in America, you can't be a Black supremacist, more like a Black nationalist. It's a definite oxymoron.
That's not entirely true, while it's very unlikely for someone to be able to provide racial laws that are similar to the laws that black people had to go through in the 18-1900's, there are many black people with economic power now. While definitely not as much as their caucasian counterparts (which would be impossible anyway since we only make 12% of the population), there are many ceo's of businesses and organization that are black.
And if these individuals believe in the execution of this agenda at their company, than yes, it would be black supremacy.
A non business related situation where black supremacy would take place is the incident that happened not too long ago regarding the stepping competition. For those that doesn't know, there was this competition where
an all white female stepping team won the competition, but many people were
upset stating that white people shouldn't be allowed to win because it feels
like they are "taking our sport" (which sounds eerily familiar to many of the statements caucasian people made to justify the inclusion of black people
in regards to different genre's such as sports, music, art, and the like.)
Now had the organization actually completely reversed their decision and gave
the winner to one of the black team members, than that would've been a perfect example of black supremacy. What happened was that they split the
title between the all black and all white team.
So ultimately, black supremacy is definitely possible, just not on a full country
wide scale like in the past for how white supremacy mangled the entire country.