Thinking about this more, I don't understand the importance of your fair-weather mining idea. If the parties collaborating on the ES attack are willing to betray each other, then isn't a much simpler form of betrayal to steal the block that someone else in the group found and claim it for yourself?

Bitcoin attempts to create a protocol that doesn't require trust between parties, but needs to robust against large groups (e.g. blocks of Chinese) who trust each other. So I don't think it's ironic that the ES attack is not incentive compatible, nor do I think it's really a flaw.