For home network printing, one way to get around such nonsense it to set a wrong gateway ip to the printer. This way, your printer is still detectable on LAN network, while it can never connect to WAN (or internet) to update any firmware
Myself I run Samsung (HP) CLP-365W for over 10 years with cracked firmware for endless refills. The hardware itself is very good, just had to rotate feeder pull rubber to fix paper problem, but that is all.