I often see the excuse for Sinister, Apocalypse, and Mystique somehow being good to kill because all the people they ever killed was for some great cause - and not ever for their own bias or sadism. lol
These guys are just more popular & tend to have better stories, so they get more pass.
FOR NOW, it seems like Hickman needed a fall-man to build his world, and used the chance to have Creed Put on A Bus.
I don't expect this punishment or law to come up again too often -if ever. If another mutant kills a human it'll be excused for good reason. I'm fine with putting Creed on a bus because he has been overused for too little. But make it less obvious. lol