Well he is involved in this to a certain extent as he was apart of the bonus material, was treated well by both Reynolds and Miller, welcomed on set and these are three of his his pride and joy characters . Which is why it's far easier for someone like James Gunn to speak on it.
Clearly he won't be choosing sides or burning bridges adding to the flame as he was a fan of both of them, I assume JKR meant just a simple "thank you and sad to see you go" or something along those lines. Lifeld is a pretty vocal and supportive dude, so the fact he isn't saying anything at all says alot. But yeah at this point best to stay silent and out of it regardless.
He doesn't need to get himself involved right now and cause more attention, and I'm sure he will speak up when he feels it's acceptable.