As David puts it is fact. I am permanently logged in and have downloaded and installed Enterprise and Pro from the Insider. I registered for the Enterprise download, as requested. After reading David's OP, I logged out on the site and went through the procedure again. I had to log in, which, presumably, has been recorded, and was still asked to download the OS to participate. Bit of a Bug on the site, possibly, but it could be a nightmare for MS to try and change the message just for retuning participants.