Why is it that creationists say carbon dating is unreliable and then use it?

There's a news story making the rounds that a group of evangelicals have found Noah's Ark on Mt. Ararat... again... Anyway, they claim that it's the Ark because wood fragments found at the site were carbon dated to around 4,800 years old. There are a lot of things wrong with that statement but the one that seems to stand out the most is that they are seemingly trusting carbon dating. I thought creationists said carbon dating was bogus junk science that didn't work? What happened?