Fish doesn't necessarily need thicker skin, or at least wouldn't, if he's stop running his mouth off and actively trying to piss everyone off. If he wasn't notorious for comments like Japanese game devs suck, or my personal favorite "suck my dick, choke on it," this wouldn't have ever been a problem. Fish brought the abuse on himself, he has nobody to blame. And honestly, what Marcus said wasn't even that harsh, especially given some of the shit that comes out of his mouth. All he said was what most of us are thinking: If you didn't have a comment on the situation (Xbox One self publishing change), then just say "No comment right now," and leave it at that. Don't get indignant over it.
Also should point out, nobody forced Fish to respond to the abuse he got, but he did, constantly. I've never liked Fish personally, because he's only ever made Fez, and believes it was a revolution for indie games, when it's anything but.