What could they do?
The NFLPA will fight everything they try and blame mental health issues, which is likely true to begin with.
CTE
Could certainly investigate the Patriots for collusion if a player was actively making an effort to get cut to sign there.
Surely there's a good probability that he directly or indirectly gauged interest from New England before blowing up his contract.
Not to mention what's to stop other players who aren't happy from their contracts in doing this?
Instead of guys holding out for their contracts, it makes more sense for them to just do this so they can get cut and become unrestricted free agents.
It's a slippery slope, but regardless players shouldn't be able to manipulate teams like this when they're under contract.
On a side note Tom Brady asked Antonio Brown to come live with him and Giselle