Yes, Rick invited him. He'd been posting comments on John Knapp's (now Mike Doughney's) TM-Free blog before that. And of course I never said he was writing "for posterity."
And yes, that's my understanding, that he considered it an exercise for his own benefit, to interact with other TMers and former TMers after his 25 years of seclusion. He made that clear in his posts. Gutsy move, knowing many of the participants would be aware of his disastrous past. As I understand it, Robin decided to venture onto FFL as a result of an invitation (from Rick?) and as an exercise, a sort of meta therapeutic venturing forth in the form of this internet forum. I don't think he had really investigated this type of format before other than for a few months on the alt. blahdadeblah (can't remember the name) forum. Judy will know all this history. But I don't think he wrote what he did at FFL for "posterity". This was pretty much an exercise for his own benefit. At least that is how I remember him talking about it.