Definition of racism
1: a belief that race is the primary determinant of human traits and capacities and that racial differences produce an inherent superiority of a particular race
2a: a doctrine or political program based on the assumption of racism and designed to execute its principles
b: a political or social system founded on racism
3: thinking black panther is a mediocre movie
4: racial prejudice or discrimination
he probably chose that specific definition because it leaves out racism towards white people. which he didn't need to do, no one is going to argue with him about it on that message board. so immediately off the bat he shows that he did not understand the audience he wrote the post for and sabotaged himself, and spent the next two pages trying to argue semantics.
edit: also calling it bullying was the dumbest move. no one likes a bully, no one who is socially constructive wants to be a bully.