Basically you have two options:

1. Take mediation as instructed by the doctor, and lower his cardiovascular risk.
2. Ignore the doctor's recommendation, and accept the increased cardiovascuar risk (about 30% increase).

Since he already tried life style changes (including diet and excercise) with moderate sucess, and TCG still remains high, he may benefit from medication prescribed by the doctor. But if you think he can try harder on diet and excercises, go ahead try it. You know him better than anyone here. Some people just wont be able to optimize their TCG level by life style changes alone. But the final decision is yours.

Sorry, can not type Chinese now.