I've read a lot about him and those things are pretty much common knowledge by now.
I would not go so far as to paint Manning as 'weak, gay, sexually uncertain', but I definitely would think twice when confronted with his history if I were to give him some clearance level (not that I'll ever be in a position to do so).
Manning strikes me as someone that has a pretty highly developed sense of what is right and what is wrong. US foreign policy is not just 'unethical', I think it transcends that several levels at least.
The main reason why the US Government is going after Manning is not because it distracts the attention from US foreign policy, but mostly because he made them look like fools.