They are just leveling you internally against some internal metric. They might have a lot of well qualified non-senior in title folks. Bringing you into the club may ruffle some feathers. It will depend on how isolated the teams are and the cross communication requirements.

If they say you are not senior ask where on the scale you fall as a non-senior. Then ask for their rubric that describes the levels and the promotion requirements. All of that should be standard and is fair to ask. Say you need it to determine next steps.

That'll give you the information you need to make a decision.