I don't think that the vast majority had major issues with a decision to move on from Oshie. The problem would be the return for most, and that was on how badly Armstrong handled it.
He let it get to the point where is was change for the sake of change, taking a big hit in value in the process.
I think he assumed that the Kessel deal wouldn't happen, and that's why he was content to wait and then have the Penguins pushing hard for Oshie. Pittsburgh got Kessel and it meant no market for Oshie, and, instead of standing pat, he pushed on with a trade when it's the worst time to be doing that (after UFA opens when teams have largely made their trades at the draft and filled out their rosters in UFA).