I need to quit flying planes and go to law school. And the FAA Chief Counsel needs to clean out old letters. At some point in this discussion I was thinking a private pilot could only log time when they were sole manipulator of the controls. That is not the case. Since the reg referenced in A squared letter doesn't exist anymore, here a more up to date letter.
http://www.faa.gov/about/office_org/...2/Trussell.pdf
It's a screwed up system but it's what we've got.