Seeing as their candidate can't win, I guess they have nothing to lose. You're right, Arnold supporting FReepers could risk losing the support of the McClintock voters if and when McClintock drops out. If Busta-MEChA wins by 20 votes over Arnold, I guess the Arnold supporter screwed up.
This a forum with thousands of members in California -- the clear majority of whom support McClintock (according to the running poll). The race is within the margin of error.
Attacking the people you need to convert is suicidal.