I must've missed where he claimed that he didn't do those things? Their specific methods were always suggested to be something "like x" rather than exactly like it.
Further, he didn't need a method that worked at identifying all people (as tripped up 90% of people in the linked explanation), just this particular one.
I run a forum and often try to identify/discourage PITAs. Sometimes just tracing an IP reveals nothing but the ISP and location/exchange, sure, but other times it'll give me an employer and so on. Trace an IP, get something like accessplus.weblink.telstra.net, recognise your pal's Access Plus business name and you're on your way.
Revealing the method goes some way towards informing future trolls of tricks available to them.
To me, it seemed that the mysterious method referenced was half about luring the troll away from Twitter/etc to a place where they could directly record the IP address. The rest came from there.
Picking out something like this to discredit the entire account is very rough, IMO, and I flagged this story FWIW.