I feel he should have an equal say in the decision
The man in the relationship can something but the woman doesn't have to listen. The embryo is growing in her not him. The man has no say so in what the woman does with her body. If she decides she doesn't want to carry the embryo that is her personal choice. You cannot tell a woman what to do with her body, you can suggest something, but don't tell her she needs to do this and that.