If a glider pilot has asked for FIS and declared himself "manoeuvring below 2000ft at a particular location" or words to that effect, I'd expect the local FIS controller to have passed this information to the Jag - who should then either re-route or at-least know to stop ***ing around trying to get the No.2 electrical system to work after it's dropped out for the 3rd time in 10 minutes and keep his head outside.
I think that you'll find that a lot of military pilots have done gliding at some point, and are quite aware of what you're up to - but it still helps for them to know roughly where you are likely to be. (The same applying to the rest of us as well, whatever the airspace rules say about see and be seen.)
G