Security flaws are one thing, and I don't disagree with the very valid point you make in that regard.This is purely hypothetical but suppose there was an attack vector into your iPhone via the Bluetooth connection made to the AirPods. Obviously, Apple would not want to allow this to remain unpatched.
But here we're talking about changes made in the sound performance of audio equipment, which almost certainly wasn't the side effect patching a Bluetooth exploit.