It’s always good to be skeptical before results are checked and replicated plenty of times. I don’t think the methodology seems too bad though. They collected data, waited to find out who the affected subjects would be, and then combed back through the data to find a common characteristic that may be a predictor. Seems solid, in broad strokes at least, to me.
As you say, though, the real test will be to see if they really can predict it now.
In my mind, until they successfully make predictions, they're still in an information gathering mode and really don't know that they've discovered anything at all yet.
People find predictive patterns all the time in past stock market data, but they got a bunch of useless trivia until they can use it to actually predict future trends.