Calling people stupid or an idiot and such is way out of line. Why can't you leave well-enough alone?! If you can't answer the guys question or help him w/o making comments like 'what a stupid question' or 'unless you are an idiot', stay away!
What got you all worked up today anyway? You've certainly got me to that point. I've never seen or heard the 'likes' of you before on this forum. You're new, or at least your attitude is. What makes you think this guy CAN'T paint? Maybe it's just the scale of the job that's new to him. Geesh! For Pete's sake, HELP someone!!!