What's the harm to us here? Nothing. I could see if Gregory was a clubhouse issue on top of having a drug issue, or he was causing dissension amongst coaches and factions were developing on the team. But none of that is happening. Gregory is apparently well liked by the team and no one seems to have any issues with his character outside of struggling with pot.
So I don't have a problem with it. I fully expect Gregory to never play for us but if the Cowboys want to stash him and see if they can get him back on the field, more power to them.
I think anyone who has an issue with this tends to just like to complain about things Jerry does in general.