No, I don't think Irving really has mental issues, at least on the level of Gregory. Two, Gregory has at least sought out treatment and help and Irving never has. Instead, Irving decided to say screw you to the Cowboys and the league and blamed THEM for his problems. Gregory has never, ever done that. He's also taken responsibility for what he's done and blamed no one else.
Why do they need to cut Gregory loose? You have failed time and time again to lay out the argument for why cutting him is the best option.