Reid is... curious about Arthur? In a peripheral sort of way. He hasn't done anything to particularly get his hackles up yet because Reid hasn't... been looking or expecting to get his hackles up. He can have blinders on sometimes when he's Doing Science To Things. He likes the fact that Arthur was so congenial about kinda just doing his own thing and didn't take the 'I want to work alone' thing as an insult.

If/when he finds out about what Arthur/Ariadne/Cobb/etc do though he is probably going to be super pissed at them. Not for the fact it's a crime (he's broken several himself and his friends have done likewise) but because it touches on one of his greatest fears – that is, feeling like he's unable to trust his own brain and intelligence. That's gonna cause some issues. I can't wait.