TRT should be allowed within natural limits. But since Bigfoot was caught abusing it, he shouldn't be allowed to take it. I think they were way too hasty with canning the TRT program, and a large part is due to the massive ignorance of exactly what TRT was. People heard testosterone and thought it automatically meant they were cheating.
Some guys *(very, very few) absolutely should be allowed to take it. Especially the older guys. I want to see them compete and be healthy until their early forties if they so choose. MMA is a sport where guys really don't compete much at all. in four years, you might average 10 fights in the UFC.
Getting older is part of life. A declining body is one of the side affects of getting older. If older guys get to use it, then younger guys should too. Getting old sucks, if you can't compete without it, you shouldn't be in the sport. If you allow it for some, you must allow it for all.