Robert Downey Jr. is Open to an Agents of S.H.I.E.L.D. Appearance

At one point in the AmA a redditor asked him what on-going television show he’d be willing to do a guest star on, and he replied:
“Agents of S.H.I.E.L.D.”
Before you get too excited, he clarified that earlier when someone asked him a similar question and said:
“Nothing is impossible. But there might be a fair amount of red tape involved in something like that. I love Clark Gregg, and am pleased the show is doing so well.”
Red tape? Could you imagine the ratings win Disney could have if they could swing a Tony Stark appearance on the show right during sweeps? I’m sure ABC is salivating at the idea.