As far as I know it, the law doesn't prevent you to go swimming with sharks wearing a sirloin steak swim suit...tempted?
Glider turning = Easy to see
Glider head-on = Almost invisible
OK to fly over as long as you know the risks and have a head on a 360 degree turntable! The sky is a big place but why make it smaller by going into known areas of intense activity?
OB