Since the rumour about the deceised Dave Kleiman being Satoshi floated around BEFORE Craig W. came out with his allegations,
No it didn't. The origin of that was entirely Wright: it came out of the fake trust documents that write created and
'leaked' to wired. It's easy to get confused about the history because wright had a series of "coming outs".
It's not a rumour that would have made any sense at all.
Why is he claiming to own Mt.Gox addresses if it's clear to people that they don't belong to him? He never worked at Mt.Gox. He did lose bitcoins in Mt.Gox's collapse but he's claiming to own the entirety of the bitcoins in that address. Because if it's not a multisig wallet, the funds only belong to you.
He was trying to convince the AU authorities he'd spent those coins on business activities in order to get a tax rebate on expenses that never existed, and he simply picked several of the largest existent addresses. He almost certainly had no idea what any of them were. Doesn't seem to have hurt him, even people who's addresses he used -- Ver and Cypherdoc, fell for his scam.