Let them wrestle. We need to promote the sport as much as we can. Allowing a senior to wrestle JV might be one of the best things you can do for the future of your program. Hopefully, that senior will enjoy wrestling so much that he persuades underclassmen to take up the sport. That JV senior might just prove to be the best ambassador your program has ever had. By all means don't look at as wasting your time with someone who will never fit into your lineup. Instead, look at it as something we all love to do, and that is to teach the sport of wrestling.