How is M$ insulting? It just looks like a leetspeak version of MS.

It is supposed to indicate Microsoft cares only about money, which to me too, seems in the same league as microslop, i.e. mildly insulting but really not rude enough to be worth censoring.

And other insults are just words as well. It's the intention, history, connotation etc. behind words that give them meaning. M$ is meant as an insult, hence it's insulting. https://en.wiktionary.org/wiki/M$