It's not 100% required...but remember, you're in HPTA shutdown; ask your Doc what he plans on doing about it? It's way more then just sperm and shrinkage. Your testicles can and will end up being two tiny lumps of flesh and your sack will be extremely tight in end stage (that's not a pretty picture in my or my wifes book

).
If you ever want to re-start you need it.
If you ever want children you need it.
Plus, hCG tells your testicles to produce Pregnenolone...which you need for all your other horomones and mental acuity.
If he doesn's want to provide it for you there are clinics that will (plus I'd look for a new doc but that's just my opinion).
You need it; trust me.