That is a great solution. I found that I can go to http://IPAddress/net/net/sntp.html and disable SNTP. I also scrambled the Primary SNTP Server Address, and put the synchronization interval to as high as it would go; 100 hours.
SNMP is completely different than SNTP. SNTP is basically just a minimal NTP client that just queries the time and doesn't attempt to do anything like compensate for network latency or use multiple NTP servers.
This is the real solution. Pretty much all printers accept read/write from public by default and share a lot of info about themselves. Any program on your computer could do this if it wants, the only surprise here is that it took this long for anyone to bother.