Since Jon had the ability (or luck) to figure something out quickly it doesn't mean he has to share what he just learned since it wasn't prior knowledge and he didn't start out knowing more than Arin.
Yeah, where I fall on this debate depends on whether the playthrough was primarily a competition or primarily a means of entertainment for the viewers. If the former then I don't see why Jon should be obligated to give his opponents tips. Plus, Arin is kinda dumb so I don't sympathize with him if he can't figure out a game's mechanics.