I think it is probably infected, but not tetanus. I think I would go ahead and get him to the doctor for antibiotics. Infections from puncture wounds are particularly bad, because they can form abcesses under the skin with nothing showing from the outside except heat and redness.
Tetanus and lockjar are the same thing. He should get the tetanus shot. If he contracts tetanus, an antibiotic will not do the trick. The antibiotic will just kill the bacteria, leaving them free to release the tetanus toxin into his bloodstream. Tetanus does have an incubation period, so he has a little time.