I was at The Next Hope over the summer, where they had Adrian Lamo on a panel along with Emmanuel Goldstein, Kevin Mitnick, BernieS, and Phiber Optik, discussing the ethical issues of becoming an informant. It was obviously a pretty tense panel; Julian Assange was originally supposed to be the keynote speaker the day prior, though obviously he couldn't because by that point he was a wanted man. A lot of people had really, really harsh words for Lamo, and you had to give the guy credit for knowing that and still being willing to show up.
Anyway, at one point during the panel I recall someone asking him how he came to know Manning; his response was that Manning found him after reading a little about him online, and then proceeded share a lot of "personal things" with him. The insinuation seemed to be that it wasn't anything as simple as moral opposition to the war or his role in it; the fact that Lamo left it so open and wouldn't go into details seemed to me that Manning may be gay, and was struggling to deal with being a closeted member of the military under DADT policy. If you check Lamo's Wikipedia page, it classified him as being an "LGBT person from the United States". Maybe Manning spoke at length to Lamo about being a closested homosexual, and the frustrations that came with it, especially being in the military?
I could be way off here, but maybe the reason they don't want to release the logs is more to protect Bradley Manning's right not to be outed, or to have other potentially "embarrassing" things revealed about his private life that are irrelevant to the rest of the case.