Two days gone and no ATCO responses to that? - c'mon guys!
Well, I'm an ex-controller....and bored for a few minutes - will I do?
I spent many years working traffic in a mixed airspace environment (inside and outside CAS, and a variety of different classes) with areas which respectively attracted mil and GA aircraft and gliders. What the controller sees on radar depends on the type of radar and the aircraft characteristics.
One primary radar that I used was excellent at displaying gliders - and anyone with the right knowledge and training could easily be pretty sure they were looking at a glider rather than clutter (just as they could recognise angels, anaprop and other common radar artefacts). And no-one I know ignored the targets that were displayed - they may not have provided a service in an area where there were multiple targets, but they did not ignore them.
This particular radar was not heavily processed and so all of these things could be seen on the display. However, other processing systems typically used today are designed to filter out anything that isn't deemed to be a 'proper' (and I mean no disrespect to pilots who fly things that might not fall into this category) aircraft.