Those are all questions that need to be answered before considering his next move. I went back to university in my 40s, and it isn't easy. The brain doesn't work as fast when you get older
It might be useful for him to approach a couple of construction companies, tell them the situation, and ask if they would hire him, if he had a degree. Whether they would may depend on exactly what his offence was. If he offended against a child, I doubt if anyone will hire him.
Honestly, given his age and criminal record, he would be better setting up his own company rather than trying to join an existing one. He could take on & oversee smaller jobs like renovations or additions. However, if people know that he's a sex offender, he may have difficulty getting projects.
