to allow any ip and force enable whitelisting you should use
ExecStart=/usr/bin/transmission-daemon -f --log-error --allowed *.*.*.*
I’ve tested it, that will allow any.
If I may why don’t you just remove the option and let people decide how to use it.
Anyway can you please let me know if updates will overwrite the changes in /lib/systemd/system/transmission.service
Thanks