The seal choice gates the TPM machinery, in both directions.
The store's three certificate paths are a function of the glue: present
when the store is deployed, and an operator's own path beats the
mkDefault. The absence arm this replaces asserted the store defaults NO
path -- true while nothing supplied one, false the moment something did.
The reader unit is a function of the PAIRING: present with store and
homeserver together, absent with the store alone. That pair is what
makes it glue rather than a feature of either side, and it is the case
that fails if a later change wires the reader to one of them.