I don't think Hain returning had anything to do with it. Calder is a goalscoring top 2 line player. With Calder we had 5 guys in realistic contention for those 4 wing positions; at least starting out. Gaber, Costantini, Calder, Caulfield and Blake. Maybe Calder realized he was on the outside looking in, and being a 24 y.o. transfer wanted a guaranteed top 2 line role.
That said, I'd rather have Calder than, say, Caulfield. Calder was quite good until his arm injury. Caulfield has been the epitome of inconsistency and, to a degree, lackadaisical play his entire career here. Yea I get he's a home-town kid, but still.