If we're to start declaring how people speak, can all you word nazis please start cracking down on those people who use the Q slur to refer to LGBT people? it's a literal slur, has been used to attack and harm large portions of the community, yet people will happily broadcast it.
I feel that's a better use of time than pushing offense over the word "retard" which ultimately doesn't hurt anyone and hasn't been used to hurt anyone.
I would say that "retard" is less offensive than the Q slur used to refer to LGBT people. You say there's a problem with calling stuff "gay" whereas I'm actually same sex attracted and have no issue with that. THe bigger issue is the Q slur.
if you're gonna just say "well my dictation of language is the only one that matters!" then you're just being an authoritarian fascist nazi and are literally the problem.