1. The hit was dirty. Not terribly dirty, but one of those impulsive dirty shots that can happen. If you've played hockey, you'll know what I mean. He knew where Scheif was going to try to go to avoid him, and that leg was there on purpose. I imagine it wasn't suspension-worthy, but it was done with reckless disregard at best, and with malice at worst.
The idea that he caused his injury by trying to avoid the hit is incorrect. He did, in fact, successfully avoid the hit, and that is why he was fouled.
2. If the Jets are so fragile a team that the loss of Scheifele sends them toppling into the abyss, then they were never going to make the playoffs in the first place. Injuries happen in team sports, and as bright as Mark's future may be, he is not the key element to the Jets' success or failure at this time.