Will Falconer, DVM Moderator
It's very much weighing risk vs reward in every decision around rabies. Is he in contact with wildlife species that can become rabid? If not (lives in city, your yearly rabies incidence is very low [CDC will tell you], and he's not free roaming, I'd judge the risk of the vaccine to be far greater than the benefit.
Anyone who's had seizures as a result of vaccination is at a great risk to do so again.