In all seriousness he should join the plumbing union 68.
https://www.plu68.com/Lots of guys who are project managers for major union plumbers worked in the field, learned the trade, and moved into the office. There is great money to be made. I know many guys who started their own businesses and make much more money that guys working white collar fancy jobs. Also plumbing is never going away. Everyone thinks plumbers just deal with crap. New construction doesn't deal with service issues like repair type plumbers. There is a huge demand for plumbers. Commercial work in Houston and surrounding areas is busy. If he's good he will always be in demand and can work his way up the ladder. Union just got a nice pay raise this year too.
Also if he has any interest in wholesale distribution of construction products post your email. I was a project manager in construction for years but enjoy the distribution side much more now and still get to be involved in construction just in a different way.