Sounds to me like he is ready. I take a 13 & a 14 year old hunting occasionally, and they are not ready to be on their own, but haven't been raised in the culture. They enjoy it, but haven't developed the maturity to be on their own yet.
Your son, though, sounds like he has it all together. I could only assume that a hunter that would pass on pretty nice TN deer would also be aware of what is behind his target.
I would have no worries sending him to his own stand if I were you.
The only draw back to not being with him is on your side...you don't get to be with him. But, you get to go with him, talk about what happened, and still have that connection. It may end up being even more enjoyable having the opportunity to tell each other about your own hunts.
Good luck in the morning...I'll be in my neck of the TN woods again, and am ready to let the rifle ring up something with antlers! Took a couple does during bow season, so meat isn't a necessity at this point. It's all about the big boys from this point on!