If the accusation he made has some type of evidence behind it, then this was not the way to present it. If not, and it was just an insult, gosh what a petty, immature thing to say.
But Musk - and especially his PR team - should know way, way better.
Hey, we all use the wrong language sometimes ... but doubling down especially after getting called out? This is I think a kind of Trumpian influence: when someone disagrees, just call them a pedophile or whatever.
Our tech geniuses can be given small license to lack at least some self awareness, but he should have at least enough to handle this one.
Stress getting to him :)