RA is an autoimmune disease and the inflammation causes damage and pain. There can be flareups.
Curcumin has been helpful for some. It is a natural product. That and other things can moderate the immune response. Drugs do that too, but some other things will still be beneficial. Drugs that lower the immune system can make one prone to infections and sickness. Some on RA cannot eat salads or any un-cooked food as they can have things go very wrong in their guts… your immune system is active there.
There is a pattern of low vitamin-D status and higher incidences of RA. If he does not get much sun exposure that is a problem. If he has a dark complexion, then that reduces vitamin D production. You can get 1000iu tablets, cheap at some places like Sam’s Club. Start on 3000iu per day and work up to 5000iu and see if that brings relief. After 2 months, reduce to 3000 per day the body has build up its stores.
Has he been exposed to chemicals/solvents from the flooring work? That might be a factor.
Does he take vitamins, anti-oxidants, essential fatty acids etc?
If his testosterone levels are low, that can also create issues that may worsen his condition.
Search for RA on the LEF.org site and see what they recommend. The search there will also hit research results that will be of interest.
There may be other inflammatory processes in the body that are life-span threatening. PSA, homocysteine and CRP should be checked. A LEF.org male panel include that, with T, FT, E2, DHEA-s etc. Might be a good idea to eval things other than RA symptoms.