And he's the weakest link on that line which is why he's been scratched so many times. You can't use poor linemates as an excuse when the kid doesn't even outplay them.
The reality is very simple: Nino Niederreiter was not good enough to play in the NHL this year, but the Islanders kept him up anyway.
The theory about only keeping him for the cap hit is plausible, but you have to wonder if the player would have even been willing to go back to the juniors for another year. Their decision to keep him makes more sense if they chose between assigning him to Switzerland and keeping him in the NHL. Snow said he gave his word to Niederreiter that he would be kept in the NHL this year, which is something that doesn't mesh with the idea of choosing between the juniors and the NHL as in that case the GM would have no reason to give any guarantees. You would only give guarantees if the player had another option like playing in Europe.
In any case, I think the real organizational mistake is in not making young players earn their roster spots.