There is absolutely nothing wrong with voting for yourself in a compo if the rules don't preclude you from doing so. It's not playing "the ass card" to do so, nor is it a "prick move." It's okay to have enough confidence in your own work to decide that you think it's the best entry. It's not unfair or dickish in the slightest. People have the right to vote for their own work. When people run for office, do you think they vote for their opponents? No. They vote for themselves. And that is absolutely fine and okay.
In my compos, I usually spell out rules for self-votes:
in tournaments like GRMRB, self-voting is encouraged
in gauntlets like WCRG, self-voting is precluded, but bonuses are awarded to teams whose members vote.
Both of these are perfectly valid schemes. Perhaps Will and Kris can clarify their self-voting policy in the first post.
It seems that Brandon checked with the organizers before voting for himself, which means he tried to do things above-board. He just seems to have mischaracterized the organizers as encouraging him to do so when they only indicated he had the option, which is totally minor in the grand scheme of things.
In any case, let's try to stay away from calling people pricks or asses.