It's not all one sided, that's a misrepresentation. There's been a number of people from both sides that have left or been banned. Manny didn't like the politics, but that wasn't the only reason he left. A few of those people came back under different names too, according to mods. It's silly to think Trump was the cause of political discontent on both sides, like we were all walking hand in hand singing Kumbaya before the orange one came about. That's like all the people that suddenly started believing Trump was evil simply because he got into politics...after they liked him when he was part of their Democrats, or while they were previously watching him on the Apprentice, or while he was just another rich celebrity in Manhattan that drew cheers from New Yorkers on late night shows.
Trump has always been Trump, people are easily brainwashed to either like him or hate him strictly based on a party affiliation. These same people didn't like each other before Trump came along, and people will continue to be at odds long after he's gone. It's a flimsy excuse, and it doesn't hold water.