There is absolutely no reason to feel sorry for any potential instructor who can not get a Class 1 medical.
If all they want to do in life is instruct, have no interest in any form of commercial flying but want to be paid an appropriate wage for providing instruction then it is perfectly possible to do so with a PPL.
They can instruct, and when they gain expereince, they can if recomended they can graduate to examminer.
It's all in the rules.
Regards,
DFC