To answer the first question, Maiden is not quoted in the article, because they didn't write any political songs at the time. So, apart from a single cover, where the band show only the general trend of a generation, well, there is no need to quote them on that subject.
Concerning ballots and vote, well...
I agree with LooseCanon, this is true, it can be a way of showing you don't want any of the candidates. The trouble is "blank ballot" is not recognized in most country. And basically, spoiling a ballot paper therefore means let the others decide. And I very much disagree with that.
First, we are lucky to live in democracy, where, once in a while, we can give our opinion.
Second, we are not leaving in a perfect world. You can't expect to have a candidate of your choice at any election. I think that, when you're voting, you're saying your will to go towards a certain direction of governing. But you're not supposed to accept all the government doings. I mean, instead of letting the others choose for you, at least, you can choose the less "worse" of the candidates.
Basically, it's what I did on the last presidential election in France. We had to choose between a rotten candidate (the actual president... no comment) and a racist, a despicable pig. Well I chose the rotten one and I chose democracy. It was the first time I hadn't the candidate I would have willingly vote for on the last tour. It was really a very unpleasant moment when I put my ballot paper in the enveloppe. I knew perfectly well that the next 5 years will be a political nightmare. But when the results where known on the evening, it was also really a relief to see that most of the others voters went to massively say "No" to intolerance and racism.
I think that, sometimes, a ballot paper can also be use to say "here is what I don't want".