As Sqad points out you can resist plans for your husband's release and one way of doing so is to say you could not cope with his condition - there is a (perhaps still respected) principle that patients cannot simply be offloaded/dumped back into their accommodation/home without certainty that they will be able to look after themselves or be looked after by others.
Separately, ask if they have done an antibody test and how strong their (anti-body) presence is. I am aware that, where arrivals from abroad are routinely being tested (obviously not in the UK), the virus is found to be present in some individuals but in many of them there is a strong antibody presence and the "viral load" is low together with no display of symptoms. Such cases are deemed recovered and not infectious - they are classified as recovered and epidemiologically they are treated equal to the uninfected part of the population. If that description applies to your husband then, all other things being satisfactory, releasing your husband may be justified. However, I do understand your concern as some Covid patients are very slow to recover and a small percentage (of all ages, including asymptomatic cases) go on to develop long term ill effects.