When I set my meal options to only show vegan meals, my recommended protein intake went from at least 101 g to at least 61 g. If anything, being vegan requires me to eat slightly more protein (assuming plant proteins are harder to digest than animal proteins). While it's harder to get protein as a vegan, I don't think that means the protein goal should be lowered.

Also, I agree with others that you predict user behavior very well.