I see no contradiction in ancaps taking political office. Politicians aren't the state. The police and military are.
Ask an alien in a flying saucer, looking down and trying to understand humanity. Ask him who's in charge. Do you think he'll point to a building full of old men having discussions; or will he point to the vehicles full of strong, fit, armed men, threatening and attacking others?
If you take up weapons to impose your beliefs on others, you're a zealot and the problem.
If you encourage those zealots by filling in a permission slip for the winning candidate to stand on and bark orders, you're almost as complicit.
But assuming somebody will be elected, I see no problem in trying to minimise the damage by putting your own hand up.