Why not view this purported 2-4 year apprenticeship as the initial foundation for conditioning and development rather than such a pejorative label as "health" or "only for health"?
Health may be one of the outcomes of this 2-4 year conditioning/development foundation---I say maybe because clearly other things affect health too and exercises are simply no guarantee of good health.
If you are sure this is someone you want to spend time with, focus less on the outcome and more on the process and relationship.
2-4 years? People change their minds. Perhaps this is a smoke-screen to see how serious you are about training under him or her.
Good luck in your decision.
"Its better to build bridges rather than dig holes but occasionally you have to dig a few holes to build the foundation of a strong bridge."
"Traditional Northern Chinese Martial Arts are all Sons of the Same Mother," Liu Yun Qiao