Had Sun been put on notice that the community will fork away and null his stake on the new iteration if he tries to fork with astroturf witnesses, then the action would have seemed more like an honorable and defensive move to me.

I disagree. (IFF) you subscribe to a principle-less pure power-for-power's-sake "law-of-the-jungle" (THEN) telegraphing your intentions to your rival (via threats) is frighteningly naive.