I'm in country Victoria, in a small town of a couple hundred people.
Plenty of 3rd party ISPs have been using telstra hardware longer than 6 years. In fact the local exchange here only has telstra and optus gear afaik, all the other ISPs resell from that.
What he claimed just doesn't seem right. I've never heard of someone only being able to use telstra ADSL and not any other ISP reselling...it's actually against the law and should be investigated. Competition has been around here for a long time.
The wireless tower is probably different though as it's NBN, but I haven't read into that.