He was just saying it was hard to follow, which I agree with myself. Not a big deal of course but hard to read. Those things matter when you are trying to get your opinion across, they weren't spelling errors so much but grammer errors which made it hard to read.
Big deal? Of course not. Maybe he wanted him to make his point clearer. Again another case where one person was probably trying to point it out nicely, and other people think he is being rude. You can't guess what someone else is meaning online...another reason clarity helps.