Playing devils advocate - I think it is not unreasonable to expect military personnel to wear civvies at civvie airports. This "request" is not made lightly and you should respect other peoples rules on security too! After all, many of the management genuinely love the publicity of an Armed Forces presence at airports.
Wearing Uniform, in the present situation, is no different from hanging around the Ticket counter at Luton/Stansted with a banner stating who you are and where you all mainly congregate on a regular weekly basis.
Awaiting the (thankfully written) Flak.
(Edti spelin)