Simple answer - no
The simple answer is no - you are not technically safe as firmware updates are just "printed" to your printer over the network. I used to work for a competitor 1995-2000 and can confirm that this same issue is built into ALL the network printers of that era. There was not even a password confirmation required before a firmware update.
We used to often discuss adding Network Sniffers to the firmware as we knew out kit was in military and government locations.
Most printers are not connected to the internet, so you are usually safe. Even if a virus did get to your PC and start hunting for a printer, it would still have to exactly match the firmware. And that implies someone has reverse engineered that firmware Really, to do this properly, you would really need access to the firmware source code.
There are many network connected devices that could suffer in a similar way.
(I have avoided names here so hopefully this will get past the moderators)