65a bottom line.
Acc. To reb yochonon, Reb meir holds that you made a neder to'us because the father was already dead.
Why do the chachomim argue? What's the sevoroh not to say neder to'us
Avrumi hersh, London england
Tosfos relates to your question and explains: Rebbi Meir says that it's true that if he died afterwards, there would be a Nolad problem but when he died before, there is no need to make a Gezeirah of dead before because of dead after.
But the Chachamim do make the Gezeirah in order not to mix up the cases.
All the best,
Reuven Weiner