I don’t think prison should be punitive, but I REALLY don’t think jail should be punitive. You haven’t been proven guilty of anything when you’re in jail.
All of the food served in prison/jail is dogshit and it’s not ok. Edible food is a human right. People with ethically based diet restrictions should be protected the same way that religiously based diet restrictions are.
Belief in a make believe sky-daddy doesn’t make one persons ethical dietary choices more important than another’s. Maybe the Satanic Temple can step in and help out the incarcerated vegans. That seems up their alley.