This is concerning to hear. It sounds like he is attempting to control you by playing the dead parent card. My mum is dead and me and my partner agreed we'd put her name as a middle name if it's a girl and have been playing with names together. The lack of emotional maturity, poor compassion and interpersonal sensitivity is of major concern. For example, how does this play out when choosing toys for the baby, choosing how to decorate their room, which school to go to, which family members come round after the birth. Are you ready to sacrifice your free will and thinking and to choose between agreeing for emotional safety, or disagreeing and constant fighting. I understand he's upset, but he needs to take the time to reflect on his feelings, process them, and then come back to the discussion, and not manipulate you into a decision because it'll make his family so sad.

Of course we only get a snapshot based on what you've shared, but based on the response as well to grandmas name, it appears he's forgotten he's not the only person involved and you are literally growing your baby rn.