Surely not all Muslims are so thin-skinned as you suggest? I'd find it more than a bit condescending if someone said they shouldn't criticise atheism because I might be a bit angry about it, to me anything should be fair game as long as we're not throwing punches... Also, Sam Harris is pretty well-known to be an atheist who shits on religion of any kind, I'd expect anyone coming here to know that to some degree, Muslim or otherwise. It's like going to r/atheism and being annoyed by all the atheists.
I think a lot of people's resentment of Muslims comes from the fact that we are expected to wrap them in cotton wool and treat them like bombs that are about to go off, which is it's own kind of prejudice. I think we could do with seeing a lot more Muslims who are willing to put up with a bit of criticism and provide their own perspective, but maybe being so adverse to criticism is just fundamentally baked-in? I honestly don't know.