Well, it is all in the original title. The author's conclusion of "Why I am not worried" was based on the facts listed in his article. However, given the gravity of the current situation at the power plant we can assume that even though the facts listed in the article were all correct the author has misinterpreted them and reached a conclusion that that is wrong.

Edit: Think of it as a physic text homework problem. You have various facts listed throughout the problem, but your job is to use a correct formulas applied in the right sequences in order to derive a correct answer (aka interpret data "facts"). Simply re-stating the facts won't give you credit for the problem - the correct answer will (aka "conclusion").