Definatly suggest he have vet check out the dog ASAP.... however, it makes sense to me that that poor pup is still sore and swollen up inside.
It could be possible the dog had a retained teste and the neuteur surgery is a little more invasive in that case as the vet needs to kinda fish around and find it in order to remove it above the appropriate spot (there is a bulb above the teste that produces testosterone, it must be removed
If there is no improvement at all, see vet! As always a vets advice in a situation like this is important. And if the man has gone to the trouble to research and purchase a Dogue I'm sure a 50-100$ vet checkup is well worth it to him...