“Checking in” as a DH isn’t a thing. Ever. YGBFSM, how absurd. Laugh in his face and walk away. I’d love to see that guy to call the CPO about it. A call from Pro Stans might be in order for him.
Checking in as a an JS is expected, however. Seat in back or not. You’ll ride regardless, but I always appreciate the courtesy, P or FA, of asking, not telling me you’ve got a seat in back. Not enough courtesy in society anymore.