It’s flagged for politics because some people have been trained by the outrage machine they watch to find any mention of Black people troubling / suspicious / distasteful (like, say, if there was a popular movement that said “hey, Black Lives Matter too, can the police please stop shooting unarmed black men?”), and those trained people often reflexively attack when something like BLM or Black unity is mentioned, leading to a mess in the forums that the mods have to clean up. It has nothing directly to do with Trump, though he did spend a lot of time fueling that outrage.
Skin color has always been a sensitive topic, it’s not just becoming one now.