As far as I can tell, this is a big overreaction to a misunderstanding.

I'm a developer with remote adb enabled, using it in the normal intended way (to install new builds of an Android project I'm developing, retrieve log files related to it, etc). Currently, I access this via VPN (tailscale), but it's exposed to connections (and any pre-auth security vulnerability risks) on any random public wifi network I connect to. Adding the ability to restrict this to just tailscale will be an improvement, for me.

The proposal at the top of the thread is that you specify which interface you want it to bind to, when you set up remote adb, rather than binding to every interface. Nothing in that proposal suggests that "localhost" would be rejected as a choice of interface. One person suggested binding only to "wlan0", but that was a short throwaway comment that is obviously wrong (wlan0 is less-trusted than VPNs) and obviously not what they're going to do.