I think pwno is proposing that we do it precisely because it doesn't align with our convictions. (He might advise Trump supporters to vote for Clinton.)
I'm sure I remember reading, but can't now find, an anecdote from Eliezer back in the OB days: he was with a group of people at the Western Wall in Jerusalem, where there's this tradition of writing prayers on pieces of paper and sticking them in cracks in the wall, so as a test of the sincerity of his unbelief he wrote "I pray for my parents to die" and stuck that in the wall. Same principle.
(Personally I think it's a silly principle. Human brains aren't very good at detaching themselves from their actions, and I would only cast a vote if I were happy for my preferences to get shifted a little bit towards the candidate I was voting for.)
Funny you mention that anecdote because I actually wrote it http://lesswrong.com/lw/1l/the_mystery_of_the_haunted_rationalist/w9
Human brains aren't very good at detaching themselves from their actions
Isn't that what rationality is supposed to reduce?
If there's such a small chance of your vote making a difference in the election, you should be comfortable voting for trump.