CFI's last medical was on Mar 7, 2003 which means it was expired.
Neither
of the pilots was licensed to be up there.

Any medical issued to a pilot under 40 (which the CFI was) is good for
3rd class privileges for 3 years, which is all that is required for
flight instruction. The CFI was instrument rated, and presuming he was
current he had a legal right to be up there.

Michael