let him eat and drink what he wants for the reason he wants (may not be what he told you, as he may be afraid of you judgmental reaction, that is way he gave you a victim's excuse).
dare to try it yourself, you may like it!
so many people eat and drink what you mentioned and they are nice people who do a lot to the world you live in, including the means for you to express yourself here ;)

live and let others live.
you only have this life and you are missing a lot.
:)