I too don't understand not buying gifts for babies. Just because they are tiny why shouldn't they have something nice be done for them?
DB doesn't see the point because any gift that DD will get personal enjoyment from will be forgotten and outgrown quickly. She won't even understand what a gift is outside of "Ooh, a new thing to chew on". Any gift that helps take care of the baby ie: clothes, blankets, buggies, is really for the parents. But in the spirit of being a good uncle he still got her a gift to play with even if she only enjoyed it for a few minutes before becoming enamored with the wrapping paper.
I agree with Aeroflotgirl. It's a deliberate snub on FIL's part. You don't buy gifts for every other baby except for the one you just so happened to insist was aborted earlier that year. It was certainly not a "I see no point" or he forgot. He did it on purpose, and if it was my parents we'd be having words. I would be seriously contemplating going back next Christmas. If he doesn't want to see her as family, fine. He doesn't have to see her, and it's highly unfair to make a child experience hurtful rejection every year for the "crime" of being born.
Birdsgottafly's bizarre need to be victimized and wounded here aside... Her situation of supporting the parents in other ways doesn't apply either. He hasn't been supporting the OP. He told her to abort the baby. He has been against this child before she was even born, and has made it very clear that he doesn't just disapprove of the situation, he disapproves of his grandchild. That's an attitude that either needs to be nipped in the bud, or the child needs to be kept away from him. Even if he begrudgingly buys a gift because DP makes him, he can show his disapproval in other ways, such as exclusion, getting a cheap/bad gift, and showing favoritism to the other children. Children aren't stupid, they catch on pretty fast.
It's not just DP's problem to solve, it's also OP's. It's both their child, and she doesn't have to just idly sit there letting her child get mistreated because DP doesn't want to create waves. I'd flat out refuse to go there or let DD be exposed to that nonsense. Though, by the sounds of the car conversation when he asked where DD's gift was, it doesn't seem like he's going to let this slide either.