I don't get what you're saying.
The point isn't that the proposal was voted down. It's that Kerry lied for years when he said he'd resigned before the KC meeting and didn't attend it. His campaign only changed their story after the FBI reports came out.
The point is that the wording you showed would give a reader the impression that the Washington Post was showing that Kerry was part of the planning for violence, but the rest of the sentence shows that the WP seems to be clearing him of any part of that.
If only the part you printed is the end of that statement, then your point about Kerry's forgetfulness is significant. If the part left out is included, then it makes Kerry look like some kind of principled, non-violent dissident who resigned rather than continue. Unfortunately it works in Kerry's favor, and his forgetfulness is not that important.
It's more in keeping with the Washington Post and its traditional sympathies.