I updated a subsciption of Norton Antivirus 2001 about three weeks ago with no trouble, so I don't think that info is 100% accurate unless something drastic has changed since then.

because the person on the phone tells me that the latest viruses can attack your PC and disable it

I believe there was a bug (exploit) with previous versions of Norton AV that allowed malicous code to disable the Norton engine and then infect the computer with whatever virus the coder wanted. I assume that a LiveUpdate patch would have dealt with that but one never knows.