Well I might as well put in my $.02 in for the motorcycle group,(I was pm'd to this thread

).
If he was a smoker he would not be a good Candidate for implants.
Since he's stopped smoking, implants maybe useful in his situation.
The diagnosis for dentures maybe correct, I wouldn't know without seeing the data from the exam.
Lets assume that its correct, then I would look at a full upper denture with a full lower denture with implants.
This will let him 'snap' the lower denture,(which usually has retention, and function problems), into place.
If natural teeth have 100% functional Efficiency, dentures usually have between 50-75%.
Using the implants will increase the efficiency.
The only problems,(besides $), is that the implants, like teeth, have to be cleaned. If he doesn't clean his teeth now what will make him do it latter.
If you want a second opinion have him go to a periodonitst,(gum doctor

). He will tell him if they can be saved by splinting, bone grafts, hygine care, etc.
Hope this helps
cya
Jeff
ps
for your viewing pleasure