Also, the Eurofox is a lousy tug. It can't handle the heavier two seat trainers, especially with no wind and wet grass. Although the impression you give is that it would not be used for tugging, but just converted so it could tug to satisfy some arbitrary requirement at your airfield.
Sounds like your son is looking to get a CPL, he would need an EASA PPL would would need to be done in an EASA aircraft, which the Eurofox certainly isn't.
If he was looking to train for an LAPL in the Eurofox, be very careful, as any down time of the aircraft can seriously hold up flight training wasting more money, time and effort.
I really do not want to crush your enthusiasm, I just think you need to explore a different route, and that this instructor may have been looking for someone to get a new tug for the gliding strip so has fed you the lines that are best for him rather than best for your son.