Why does the media insist on calling Creationist Science an 'alternative' to the theory of evolution?
That's like saying pancakes are a good alternative to an internal combustion engine.
I'd say it's more like astrology as an "alternative" to meteorology or astronomy.
I suspect a laziness bias, or ignorance, or unwillingness to offend readers (a distressing number of Americans are creationists, after all. A headline like "Religious Extremists Attempt to Subvert Science Education" would doubtless annoy lots of readers).
Look at it from the reporter's point of view: we're long past Scopes, when the creationists wanted to forbid teaching evolution; these days, their best bet is to get creationism (under the name of Intelligent Design) taught alongside it. Actually, after Dover, we may even be past that point: the new scam from the Discovery Institute is "teach the evidence against evolution". But a lot of rank and file creationists haven't gotten the message yet.
Since they can't just get rid of evolution (yet), they need to get their foot in the door somehow, so they present creationism/ID as an "alternative". That sounds nice and fair, and since the party at the focus of the story said it, the reporter feels justified in using that term. And besides, the person calling it an "alternative" usually has a Ph.D, or represents a group with an innocuous name like Citizens for Academic Freedom and Baskets of Puppies or some such, so hey, let's go with it.
Ignorance: the Discovery Institute has had years to perfect the art of masquerading as scientists, and they've gotten rather good at it. If this is the first time creationism has come to the reporter's town, he or she might be excused for not knowing its history, and thinking that there's something to it.
Journalistic principles: while many newspapers may be biased one way or another, in the US "bias" is a Bad Word, so they at least claim to strive toward impartiality (heck, even Fox News calls itself "fair and balanced", not "news for the right"; that wouldn't go over well). There's a tendency in the media to present both sides equally and let the readers decide, even when, in the words of Stephen Colbert, "reality has a well-known liberal bias". It just isn't done to say that there's a dispute between A and B, and B is obviously wrong.