paulo
Hmmm, I didn't know that was a thing that was possible. Sounds like it might be worth a try. Would this would also mean that the offline pc not having antivirus software (because I didn't need it) would not be an issue because it's on the laptop or is that too much to ask?
Antivirus is only good for spotting local infected files. That is not network related, if you feel safe when you copy files from USB stick, network connection is not going to increase the risk.
For safety, disable (not enable) "Files and printers sharing" on that PC. But that is just a part of the following:
Not updated OS is potentially vulnerable for local (and only local!) network attacks. So if your Notebook or ANY other computer in your local (!) network (if not sure, temporarily switch them off) is currently infected, you put your PC under risk. But if your laptop is the only computer in the local network and you are convinced it has no viruses, your PC is safe (even in case is has vulnerable OS version!).
There is one potentially problematic point: as soon as you connect the PC to the Internet, almost all programs (including Windows) will try to look for updates... It can happened something is "successful" with that activity, and as with any changes that can trigger instability. So make a complete backup or at least create windows restore point.
All that are paranoic pessimistic scenarios. If you ever connect an (even "empty"!) USB stick from clients/friends to that PC, the probability of "harmony destruction" is many times higher then from proposed network connection