A very interesting thread, as I have also have been cleared to transit within MATZ not above 500' QFE (within the ATZ) over terrain that was higher than that of the aerodrome.
Afterwards this led made me think that maybe I should not have accepted this clearance as this meant I had to fly slightly below 500' agl although the aerodrome circuit was very busy with multiple FJs all at 1000' QFE. After consulting the Rules of the Air Regulations it does state that 500' in reference to Rule 5 RoA is measured in all directions and not just the vertical. This leads me to believe that unless your landing or taking off from a Goverment or licensed aerodromes in the UK then regardless of an ATC clearance you should not fly below 1000' of the height of the heighest obstacle within 600m of the aircraft when over a congested area or within 500' of persons, vehicles, vessels or structures which practically speaking means that you should not fly below 500' agl in the UK surely? unless your over a remote area.
Going back to the original question, IMHO no I don't think your being pedantic Cyclically, it shows an awareness that military controllers are not always familiar with the civilian regulations and a clearance offered by them does not necessarily have to be accepted as offered.
