I wasn't able to recreate either the asound.conf file regenerating in /etc/bluetooth on my 12.2 machine here, but to be fair I made quite a few Bluetooth-related changes on it. I thought it would be a function of BlueZ when it starts up, but that doesn't seem to do it. Are you running any sort of software or scripts that might be attempting to auto-detect BT audio devices?
As for the linking of the asound.conf file, this was sort of a compromise made on Patrick's side. When I submitted the BlueZ scripts to Pat for 12.2, I mentioned that the asound.conf file he was currently putting in /etc/bluetooth was supposed to be going into /etc, so that ALSA could pick up any BT audio devices. I suggested either putting it into /etc where it was intended as a .new, or at least putting a README in /etc/bluetooth explaining what the user would have to do if he wanted Bluetooth audio to work.
Neither of these would have been ideal for a few reasons, so Pat decided to instead just symlink it to the file in /etc/bluetooth in the package's install script. I suppose the idea was that this would work out of the box, rather than having to deal with a .new file on a fresh install.