Solid proof that the guy in the bas kol is older. Why does it say “bas plonis”? Because she hasn’t been born ywt, so she has no existence to mention. Therefore, she is refered to as the future daughter of somebody real. But it is “l’ploni” – he already exists.
He’s probably at least 11 days old at that point or he’d be called rach. So there is a solid year age difference right there. The bas kol seems OK with it, too bad for AZ