Advice

This guy and I have been dating for about 2 months now. He wanted to make the whole thing official (bf & gf) after a month but I shut him down and told him to wait. I spoke to my grand mom about it and her opinion was inorder for the relationship to be official he should go to my dad and ask his permission to become my boyfriend out of respect. Now I agree he should but not for the same reason as her, my reason is because of the situation our dating relationship started off on seeing that we have totally different background religiously and culturally my dad isn’t too fund of him so I thought it would be a good idea for him to sit down and get to chat with my dad so they get to actually know each other a bit and he’ll see that my guys intentions aren’t to harm me in any way. The thing is the guy believes that he shouldn’t have to ask ‘another man’s permission to go out with his daughter’ he says he’s a grown man and shouldn’t have to ask to take me out. This disappointed me a bit but I want to know if I am wrong to agree with my grandmom and want him to sit with my dad so he can get a better shot at making a good impression or not?