I don't know if I'd go as far as say JMS chickened out on that. Sheridan resigning from Earthforce, for instance... it showed that he was right, but he did it the 'inconvenient way', politically. Doing the right thing comes at a cost sometimes, and that was his. (He was able to get his crew cleared of amy wrongdoings, so he was being a good leader on that front, too.) The fact he was voted in as the first President of the ISA is immaterial to his conversations with Earth.I liked everything except Brand New Day, and that's not on him. It's on Joe Queseda's incompetence.
I think my main problem is that JMS kept chickening out on some plotlines that seem like they're going somewhere morally ambiguous but always goes back to "Nope, the main characters are always in the right and any chance they could be wrong is zilch!".