if he was a broker and decided to try trading his own acct., he might not want to park it @ a prop shop as there is a stigma attached if he later tries to/needs to get back into that game. so, if not @ a prop shop, it's quite difficult to find someone who will let you hang your license without being a full time employee.
when i went off on my own as an RIA with a 65, i did not and did not want to do transaction (ie: commish) biz, but would have preferred to keep my 7/24/63 active nonetheless. given my RIA status, related SEC requirements and the lack of a willing BD, i ended up having them all expire- not my ideal.
my situation was 13 years ago, so you've got more options. what i will add is that it is easier to find someone to 'hire' you with a current license (which will reset the clock) than find someone to sponsor you to go thru the pain in the ass of testing for a new one. not just your 7, you've prolly got at least a 63 also. don't let it expire if you think there's a chance you'll need it later.