What you don't seem to understand(because you've never even looked at the CBA and that's very obvious), is that personal conduct of players is not something outlined in the CBA. It is SOLELY outlined in the standard player contracts that players enter into an agreement with their organization. It has nothing to do with the CBA. The only thing the NHLPA can do is see if the Hawks violated the terms of Perry's SPC, as there is nothing in the CBA that they would have violated. If the Hawks didn't, then that is the end of it.
You need to educate yourself.
The CBA between the NHLPA and the NHL sets out the terms and conditions of employment for all professional hockey players playing in the NHL, as well as the res
www.nhlpa.com
The MOU is what actually outlines benefits of players and such and rules regarding salary, insurance, etc.
And the MOU also does not contain anything with regards to player conduct. Again... that's all part of an SPC, which is between the club, and the player, and has zero bearing on the CBA.