A couple of people worked on that in this thread
https://www.mobileread.com/forums/sho...d.php?t=122704
I think their general consensus was that a log file is being generated but they couldn't find where it was ever actually going to Amazon. It was agreed that the file was too big to imagine that Amazon was actually collecting these from every single Kindle user on a regular basis.
But if you're concerned about it Yifanlu came up with a modification that inserts a faked ip address in place of Amazon in that line of code.