They might say this because they don't want to license MacPoET or EnterNet for the OS 9 users. OS X has PPPoE functionality built-in, whereas OS 9 needs a third party program to do this. If he can get ahold of MacPoET or EnterNet he should be able to connect just fine. Better yet, get a router and he won't need to deal with PPPoE at all (just set the router to connect via PPPoE.)