Would like to have Hardy's talent back...but not his troubles. He's still available for a reason, despite his pass-rushing prowess (and even in a market that has vastly over paid the likes of Vernon & Jackson).
Don't completely agree that Garrett can't handle players with issues. Within the last couple of seasons...McClain, Scandrick & Gregory, have all been suspended for drugs. They weren't 'late'...they were 'unavailable' to the team for 4 games. Yet they brought McClain back again & support the others. Dez has a unique & sometimes strong/childish/volatile personality...yet Romo, Witten, Garrett, and so on, all love him & he got a big extension. Dez, McClain, and Gregory, were also all brought in or drafted, despite knowing their past history/issues...as was Hardy. Only the PR hit for Hardy was significantly more substantial and long-lasting, and I think he proved to be a different animal so to speak.
Garrett (like any coach), wants to win & keep their job. He knows Hardy could help. I think it's more than Garrett that has reservations about Hardy returning, and I think there's more to the story. Jerry took flack for defending him and calling him a leader. There was talk of wanting to resign him longer-term from the front office. That all seemed to essentially vanish by seasons end.
If they were to resign Hardy for 1 year ala McClain...do so with behavioral clauses/incentives built in. And structure it so it allows the team to cut bait at any time with little loss (guaranteed money), for conduct detrimental to the team. Lay all of the guidelines out, and if he elects not to accept them, he simply doesn't have to sign on the dotted line. If he signs & then breaches the contract, he's gone.