Nichushkin hasn't been charged with a crime and he's not under investigation:
Source
The NHL knows what happened, has said Nichushkin is eligble to return and that the Avs handled it appropriately (not that the NHL is trustworthy on disciplinary matters, but they aren't going to move the needle).
The Avs are insisting on treating this as a private, personal matter, and until we have more confirmed details or something happens like Nichushkin being charged with a crime, second guessing that is just speculation.
It seems this story is on track to die out unless some reporter decides this is their big story and gets to the bottom of it.
He'll be back next year and reporters will ask questions and get a bunch of non answers. If Nichushkin plays well eventually the fans will forget about it. If he doesn't fans will use this to criticize him. I suspect he's going to be motivated to make it up to the team for not being available during the playoffs.