Disclaimer: I'm not a con, so I can't speak to RB's experience
![Stick Out Tongue :p :p](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)
But... he uses what he has access to.
The best fake IDs are real. I assume he is taking existing IDs and documents, and altering them slightly to create new aliases. The evidence is that many of his names are simply variations of previous IDs he's had access to.
Why those names in particular? I suspect he is stealing them overseas, altering them and using them here, and vice versa.
I don't know if he is also stealing wallets, homes, financial and real estate records, but some of these names might be altered from previous victims. I don't doubt he tried to use JO and Marion's documents to make new aliases for himself (and accomplice), to use overseas.
He also sometimes uses deed poll to change his name. So yes, he could chose ANY name. I can only assume he has stolen real documents in these names, overseas. Like Richard Lloyd Westbury. I suspect he stole that name or something like it, overseas. Once in Aus, he changes his name by deed poll so he can get an Aussie passport, so now he has (potentially) bank records and title deeds overseas in those names, plus an Aussie passport as photo ID to prove legitimacy. IDK, something like that.