It is fair to say fixed wing pilots should give gliding sites a wider berth when they are active, just as they should stay clear of the cloud base on a reasonable day at the weekend. Safety and good airmanship suggest it would be a good idea. The reality is some decide it's their 'right' or find themselves not doing so for whatever reason.
As far as I am aware pilots must report airprox events, if you feel any event was dangerous report it.
An ATZ has a legal status in the ANO as do NOTAMs and the AIP.
As a glider pilot you might like to consider; We constantly have gliders fly though our ATZ without being in radio contact even though this requirement is published anywhere you might expect to find it. We also have gliders fly through our airspace when parachuting is taking place (published and NOTAM'd). Gliders continually land at our airfield without a PPR or being in radio contact. One glider pilot recently decided it would be a good idea to land on the taxiway, not speaking to us even with working radio fitted.
Glider pilots are not alone - Recent 'fixed wing moments' include a pilot who executed a crosswind join, not in radio contact with parachutes in the overhead. Then there were 3 aircraft on the live side of the circuit, over a built up area, below 3000', within the ATZ, not in radio contact conducting a aerobatic display.
Almost every day I work in the tower there are 'moments' which do not result in anything further however, the laws of chance demand that one day this will not be the case.