If you violate the terms of your contract, you don't get to just negotiate a "buyout". You broke a conduct policy in your contract, and the contract is null and void. Hence the use of the word "termination". He's likely not going to appeal, because then exact details are going to emerge, and it's going to be an embarrassment for him and his family. The NHLPA only files a grievance or appeal at the request of the player.
And it's not the Hawks setting a precedent. Players have already had their contracts terminated in the NHL for violating the code of conduct in their contracts.
The players union's job to protect their players. The NFLPA even appealed Greg Hardy's 10 game suspension after his atrocious allegations came out.
I suspect the NHL CBA is much like the NFL's where appeals will be handled behind closed doors through an arbiter. Even then, I suspect details of the story will come out regardless of an appeal.
Could Perry may not want the NHLPA to file a grievance. That is true. However, the NHLPA could see this action far bigger issue than Perry. This is from the Daily Faceoff article:
"The big question lingering is whether Perry’s alleged misconduct has risen to the level of a material breach of his contract. For the test of time, NHL player contracts have been ironclad agreements that guarantee employment with only vaguely worded and limited exceptions that grant teams the right to terminate.
Given the lack of detail provided by the Blackhawks, it is impossible to know whether Perry’s conduct met that mostly unprecedented level of material breach. Teams have previously sent players home and continued to pay them until the expiration of their contracts, but there does not appear to be one example in recent NHL history of an active player’s contract being terminated for conduct that may be inappropriate but not illegal. The Los Angeles Kings attempted to terminate Mike Richards’ contract in 2015, four months after he was charged with attempting to cross the border in possession of controlled substances, but even then the Kings were forced to pay cap recapture penalties and termination fees to Richards totaling $10.5 million over 17 years through 2032."
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Hence, I think this will be a far bigger issue for the NHLPA than just Corey Perry. That said, I'm not defending Perry's alleged behavior. In fact, I commended the Hawks. However, it sounds like this level of NHL punishment is unprecedented if the Daily Faceoff story is true. IF so, the NHLPA will have a major issue. It's their job.