Why would the timing indicate him not acting ethically? He might just realize that information leaks are time sensitive, that when you release them is almost as important as what they contain.

If your objective is to inform the public, you get the information out with time to spare so it can be investigated and objectively assessed. If your objective is to sway the public, you release at a time of greatest impact where people's reaction to the accusations and implications will drive their actions, instead of the complete facts of the matter, which it would be silly to assume Wikileaks could provide (there's always context that can be added).

I agree wholeheartedly with this. IMO, while Wikileaks is certainly not on some untouchable moral high ground, they do good things and that's worth it for the bs Assange etc pull from time to time.