Fournicator
The answer to your question to me is no.
What would be sensible is to think about the risk before you do something. If you want to do your 4000fpm descents in Class G and there's cloud in the way and your primary radar is inop and the use of transponders is not mandatory in the airspace and it's not CAS then you have a few choices.
1. Go ahead and do it anyway
2. Defer doing it until you have serviceable primary radar
3. Defer doing it until you have good vis and can achieve separation by visual means.
4. Stick someone outside the tower with a pair of binoculars to watch out for traffic underneath the clouds and make sure it's all clear before initiating the descent.
There are probably other choices as well but of the ones listed I suggest No 1 carries more risk than the others. It's up to you to make the decision.
Please let me be clear that I am not suggesting that it is good airmanship that the gliders do not make use of facilities that are available to them (even though they are not required to do so). Rather I am suggesting that it is bad airmanship to go hooning about on the assumption that they should and will.
On the matter of radar visibility, I've had gliders called to me by radar that I haven't been able to see even when they are only a mile or two away and I was being told where to look. If your primary radar can't see them when they are within your own MATZ you need a new one.
Mike