Bengal is the region where Shakti - Devi tradition is followed the most if all over India is counted, 95+% of Bengalis are non veg including people like Brahmins. Meat eating is also allowed during Durga Puja and is even consumed so why can't Bengali Hindus ask for their right to eat non veg?
People connect that in Hinduism non veg is a sin but in various places non veg is near to necessary to be made on Holi and we very well know how much famous "Bali" or sacrifice is in our religion.