A player with 4+ accrued seasons, if released, won't be subject to the waiver wire process. They immediately become a free agent, like Brian Hoyer recently.
Gordon only has 3 accrued seasons (he dressed for 6 or more games in a season, 3 times), so if he were released he'd be subject to the waiver wire process, where any team can submit a claim... but if there's multiple claims, then whichever team has the worst record will get the player. If the Pats wanted to claim someone, they'd have to hope that 25+ teams don't submit a claim.
I wonder if part of not letting him play until week 14 was a request by the Browns to the NFL so he doesn't accrue a season.
The fact is he's already waited a month past his re-instatement application date already, so there really is no reason to make him wait another 4 weeks to play.
Add to that, the fact that he also voluntarily went into a long rehab.
Hopefully he hires sober chaperones/counselors to follow him around whenever he is out of his home.
He's basically done the hard work of getting clean, now what he gains to benefit from staying clean far outweighs any cost/inconvenience of making sure its impossible to fall.