Cf. my last edit, hope that the telnetd is still up, or do a reset to factory defaults.
It won't uninstall the hack, but it will disable it.
As for the warnings, they're here, right at the top of the file...
# Take note that we're essentially a shell script, se we absolutely *MUST* use UNIX line endings!
# Tweak these to match your setup (Do NOT modify while usb over ethernet is enabled!)
# Allow SSH over WiFi
# NOTE: If you set this to true, the SSHD *WILL* check your passwords!
# Make sure you know your root password, or auth via shared keys!
# Leave it to false on non-WiFi devices
# Don't switch to Ethernet over USB, and only launch SSHD
# NOTE: Probably only useful with WiFi devices, so leave to false on non-WiFi devices
That, and also that, in the thread itself:
Originally Posted by NiLuJe
Also note that, while there is a zipfile for the usbnetwok hack attached here, I won't provide any support for it, and I strongly discourage anyone not well versed in bare-bone Linux CLI system administration to even try it. It's far too easy to brick your device/mess up the software with that thing.