...it's probable that they were picked up following Lownie's submission of their book to HarperCollins, rather than through the Authonomy site.
The ever-vigilant Sally Zigmond has this morning spotted this comment from the man himself over on Galleycat:
My agency submitted Never Say Die by Melanie Davies and ghosted by Lynne Barrett-Lee in the normal way. The fact the authors had put it on Authonomy may have helped in Collins's decision but the editor was only aware of the script being on Authonomy after the submission. Andrew LownieGod, I'm good.
(Now, if Sally could just find out for me if the authors of the other two books are represented, I'd be very grateful indeed.)
ETA: Here's a news story which explains how HarperCollins made its offer for the book in December, nearly a month before Authonomy announced the sale.