J. Gleason:
You may be correct in your assumption but I think the question that would have to be answered in a court of law is: Are law enforcement officers that are off-duty and not acting in official capacity, still considered peace officers by definition or are they ordinary citizens? The GFSZ, trespassing, and vehicle carry statutes imply that when off duty they are ordinary citizens.
From the LEOSA law:
However, there are two types of state laws that are not overridden by the federal law, these being "the laws of any State that (1) permit private persons or entities to prohibit or restrict the possession of concealed firearms on their property; or (2) prohibit or restrict the possession of firearms on any State or local government property, installation, building, base, or park." This does not mean that LEOSA-qualified persons are prohibited from carrying concealed firearms in such areas, but only that they must obey whatever state laws apply on those two points. They are free to disregard all other state and local laws that govern the carrying of concealed firearms.
The LEOSA overrides state and local laws, but not other federal laws. Thus, LEOSA-qualified individuals must continue to obey federal laws and agency policies that restrict the carrying of concealed firearms in certain federal buildings and lands.
Note: Schools are state or local property. One would suspect that the GFZ would be considered included. Also the GFSZ is also federal law.