If I were Gruden, I'd call a team meeting tomorrow. I'd announce to the team that we aren't allowed to fine players for 'speaking their mind' on social media. But it's the coaches decision who plays and who doesn't, and any team-related post on social media, whether cryptic or obvious, would result in that player being benched, regardless of who posts it.
And they'd hate you for it.
Until they started winning, then they'd respect you for it.
When players won't respond to the carrot, you need to try the stick. You could ask Norv Turner about that, but Norv will probably never admit the truth, not even to himself.
So ask Marty Schottenheimer, and he'll tell you that if you can't unite a team by getting them to love you, you can still unite them by forcing them to hate you. It was no accident, how Marty managed to piss off two future Hall of Famers in his first few weeks in D.C., then ran off 8 wins in his final 11 games after the team finally bought in. It's how a head coach with all the flexibility of a stressed I-beam managed to stick around the NFL long enough to make 13 trips to the playoffs.
Since Gruden won't always be blessed with high-character, self-motivated players, maybe the fact that he has a chance to learn this lesson early in his tenure is a blessing in disguise.
If these brush fires extinguish themselves over the next few weeks, we'll know he took advantage of the opportunity to assert himself. If they don't, well then Gruden lacks the stones to stand up to either his players or, possibly (as tr1 said), his owner.
And his chances of winning here are slim.