I saw those emails a little while ago. Personally, I think Mr Coren is being a bit of a c--k. But then I work as a sub editor, so I'm a bit biased. I'm not saying he didn't have a point, but the issue was based around a sketchy joke that a lot of people wouldn't have got anyway, and he could have been less rude about it. If anyone spoke to me like that about work I'd done, no matter how precious the original was, I'd blow my bloody stack.
If Coren saw some of the poorly researched, badly written, badly punctuated, shoddily constructed cr@p that ends up having to be fixed by sub editors in order to prevent the writer from looking like a fool, perhaps he'd be a little more measured.