It's not a case of IFR or VFR traffic having more 'rights'. The point is that the IFR pilot is flying by the rules. Unless there's an exemption in the ANO, the glider pilot when flying at an altitude above 3000' is not VFR when within 1500m horizontally or 1000' vertically from cloud, he is IFR also and so should be flying by the same rules. Class G airspace is not "see and be seen". I agree that a RIS has no guarantee of separation, but a RAS is not always forthcoming and the whole purpose of flying quadrantals is to minimise conflict. At the end of the day, rules is rules, and they're there for a reason.
The power pilot will, or course, give way to the glider. But he needs to see him first. Gliders are difficult to see at the best of times, and scudding around near cloudbase surely isn't one of them. Of course, they might be easier to spot if they're a mile away from the nearest cloud or a 1000' below!