Riiiight. To get back to his possible sleep disorder, the OP's DH may or may not have RLS, because HE seems to be able to sleep despite his leg twitches. Which is not typical. But it could get worse over time, as mine did.
I had it for many years and it gradually worsened until I could only sleep in 15 minute naps at best. And yes, I tried all the home remedies suggested, exercised, cut out caffeine/alcohol, took magnesium, quinine, melatonin, gels, whatever I could get my hands on. Nothing worked.
My GP prescribed Ropinirole which I've now been taking for a few years. It is not a cure but a daily tablet means I can sleep. If his legs get worse I would recommend giving it a try. Perhaps when he is thrashing about so much that it disturbs him too he may realise he has a sleep disorder.
Perhaps continuing to sleep apart may give him an incentive to sort it out.
(My DH was a saint, he can sleep on a fence
but I did disturb him a fair bit)
Best of luck, OP.