Firstly, this isn't exploitable at all. Just set a minimum experience threshold ex. Account Is at least one year old with at least 1000 qi or something to that effect. Then you just open a discussion thread and you do all the voting there so that there are no loopholes.
With that being said this is a terrible idea, and I actually kind of have the same reasons as bod. Basically my only issue with it is the fact that A. It becomes even more of a popularity contest than it already is, I call it the "high school election fallacy," because all logical reasoning goes out the window and the most popular candidate pretty much wins 100% of the time.
And B. The gm's know how to be a gm better than the rest of us; therefore, giving inexperienced normal users any kind of weight on the situation is really just slowing down the process. This applies mostly in small communities btw, which kyure mentioned, because most of the names on the ballot are probably familiar for one reason or another; whereas games like runescape(assuming they elected their staff) would never have this problem because there is little to no chance that a person's username would be recognized globally(in gaming terms not literally).