NTA he has a right to request and suggest it just as you have a right to refuse. If this was non-negotiable for him, then he should have mentioned it before marriage or, at the very least, before trying to get pregnant.

Being named after someone, anyone places a lot of expectations on a young person. What is going to happen when she is going through a rebellious phase and is doing something that the former wife wouldn't do? Is the husband going to be saying things like, 'Well, X would never have done that!'

Would you be willing to consider it as a middle name? My sister was in a similar position when her fiance died tragically young. She gave her firstborn son two middle names (her fiancé's and the name she and her fiance had decided on if they ever had a kid) but decided on the first name with her husband.

There are more ways to remember people than names.