According to Jared Cowen's agent, Rick Valette, he's good to play hockey right now. A part of the Dion Phaneuf deal, Cowen never played a game for the Maple Leafs, first sidelined by a hip injury obtained when he was playing with the Senators, and then sidelined by a case of "we don't want you".
The Leafs are going to buy out Cowen, which is part of the reason he's been sent home: you can't buy out injured players.
On one hand, it's harsh - especially so with the trade deadline having come and gone, and nobody else wanting Cowen either, evidently (at least, not for a price). But on the other hand, at least it's honest, and gives him a chance to prepare for the future.
Valette's full comments, via Elliotte Friedman's 30 Thoughts (#5):
"We’re going to take the time to get Jared right. He’s not injured, but he’s not right. Any doctor would clear him to play. But there are compensation issues when your hip isn’t 100 per cent, other parts of your body are affected. Rather than having him sit as a healthy scratch with the Leafs or the Marlies, we’re going to have him go see some people and get healthy."
Cowen is back in Ottawa, but Valette plans to send him to the Mayo Clinic and some other specialists he knows. Damien Cox reported Saturday that Toronto granted him permission to speak with other teams, but Valette will wait until seasons start ending before pursuing them. "He’s 25 years old. We’ve got six months to get him back to being a good player. That’s our game plan for now."
It sounds like the fairest possible solution for all involved, and hence, no grievance. At least Cowen can use this time to rehab and sell it to future suitors that he'll be better for next season, and hopefully find a new team.