So, when was the last time you heard of a glider flying IFR?
And how does this "Control" affect squawking VFR traffic ?
For the pilots of squawking VFR traffic, such as yourself, it makes no effective difference because you're obeying the rules and exercising your right to be in that airspace without talking to anyone. Controllers are happy because they can reliably see your squawk and can apply vertical and/or horizontal separation for their IFR traffic. IFR pilots are happy because their TCAS will see your squawk too. The net result is that it's highly unlikely that any pilot will have to rely on 'see' in order to 'avoid'. But the VMC minima (8km/1500 horizontal/1000 vertical) are the backstop - and of course if you can't meet them you're IFR.
My main concern though is that the confusion you refer to airwave may lead to gliders crossing N560 non-transponder without clearance. Primary radar is notoriously poor at detecting gliders and of course gives no height information.
Great to hear Loganair's proactive approach though.