Celebrating violence that has already happened does not violate the TOS rule 1 cited by OP. Barack Obama held a press conference on national TV when Navy Seals assassinated Osama bin Laden.

Being an American citizen does not make you immune from posthumous criticism. I think OP is displaying bias based on the facts of this specific case. If Harvey Weinstein got shot in the hospital instead and forums celebrated I doubt they would have an issue.