While Mekkah is a fag, autistic, and a seething retard for all the political and public image motivation that's lead him to this point, I think he very legitimately is emotionally damaged by Mangs going "Too late" when Mekkah tried to at the last second plead for him not to do a flip. If you consider that a valid mental hang up is up to you, but I think it is a understandable reason.
I think he just wanted Mangs to learn his lesson due to whatever principles he has, keep his public image by dumping Mangs, but also didn't want him to do a flip once everyone in the community Mangs has been part of for many many years just turn on him. Have his cake and eat it to so to speak, Mekkah made the choice of his public image and whatever principles he had that suggested his actions were just, and he just couldn't accept or didn't comprehend that Mangs might do a flip due to his actions. Without Jake/CyanYoh's intervention Mangs would have literally did a flip off a bridge 9 times out of 10.
Still I think Mekkah was foolish to think that wouldn't happen, he with everyone else effectively just dumped Mangs and tried to ghost him for the forseeable future while slandering him and then he just thinks nothing will happen. This is what happens when you mix public clout and personal friendships, everyone has to make choices when you're in positions like this and Mekkah made his and he has to live with that choice. Except Mekkah literally can't, because he's an autistic seething retard.