The NFL needs to address the “hold in” nonsense just as much as holding out.
Refusing to actually participate without a clear injury should always be a fine.
Problem is does the team wants to fine the player(s), who is in the building and negotiating for a contract.
The team wants players to show up. There’s a reason they made it impossible to revoke the original fines, so the team isn’t responsible for making that decision.
Not practicing is the same breach of contract not showing up is. It should also be out of the team’s hands.
This is collectively bargained though and no way the players agree to this.
They agreed to fining players who hold out and making it impossible for teams to waive them, because holdouts are bad for the sport.
Hold ins are exactly identical in every way that matters. Being there without participating adds no value.