According to Ken Parish, Tim Blair has written to say that his move to The Bulletin was entirely of his own doing, that he will still write occasional pieces for The Australian, and that any further speculation on this issue will be countered with a nude protest in Byron Bay.
Unlike Ken, I find the prospect of Tim naked in hippie country bizarrely amusing, so I’ll assert (on the basis of extensive current intelligence from MI6 and other sources, natch) that “he didn’t jump, he was pushed”.