Well, Pettersson played nine games at C last season. I think it makes sense to ease him into the NHL on the wing. The Habs' problem with Galchenyuk is not that they did this; it's that they refused to take the next step and let him grow into the C role once he had established himself as a viable NHLer. I doubt the Canucks will be that stupid.
The boldfaced part makes too much common sense for the idiot MB Habs. They prefer to feel like special geniuses possessed of the uniquely privileged knowledge that Drouin is actually a C and Galchenyuk actually isn't.
As for putting Drouin back to the wing, they won't do that even if it were to be the obviously best thing for him and for the team, because MB has publicly committed his precious ego to the principle of Drouin being turned into a C.
These are the kinds of things that happen when your top priorities are things other than winning.