Responses to each of these paragraphs:
Murray has been playing great lately, not just last game, though it was his best. I haven't heard anyone else connect it with Nuti being away - I think that's a stretch. I will say that Harrington, though a rookie in some respects, is a real student of the defensive side of the game. There's got to be something reassuring about playing next to that, and it allows Murray to come forward more.
I think Nuti is a creative type of player. I think a little bit of AHL time would be great for him to experiment. We still want to evaluate him for the playoffs, but a month in the minors while we test out Prout and Harrington wouldn't hurt.
As for the trade idea, a late 1st + Jenner + Nuti for Duchene is an easy yes for me and an easy no for Colorado. Does Nuti have top pair upside? I can almost see Jared Spurgeon in him, but I really doubt it's enough for the Avs. They need at least one solid "build around" piece coming back and those are all complementary. One quibble: it's good to work in the expansion implications but you're missing something. What we lose with an additional player to protect is not Josh Anderson but the gap in value between Anderson and the next player Las Vegas would have picked. So it would be, say, Duchene + Karlsson for Anderson + Nuti + Jenner + first. Does that make sense?