Why do people keep saying that al-Shirri was involved in the September 2008 attack on the US Embassy in Yemen?

This quote is from a press release from Senator Orrin Hatch today:

Recently, as reported this year in the January 23 edition of the New York Times, a former Guantanamo detainee from Saudi Arabia has resurfaced as the #2 in charge of Al Qaeda in Yemen. Furthermore, it is believed that this man was involved in the planning of an attack on the American Embassy in Yemen last September. This terrorist assisted in the murder of 10 Yemeni citizens and 1 American. Former Guantanamo Detainee #372.

This is just one of the many reasons that I hate anonymous security quotes in newspapers, not to mention the fact that they often do more harm than good or are simply inaccurate. This is becoming the story that just won't die. Now certainly there is something to what Senator Hatch is arguing, and while I disagree with him and think that Guantanamo should be closed, I also think he is correct to ask what will happen to the detainees. But I also believe that it is important in discussions such as these to operate with facts that are correct, and not slant them or shape them to fit one's argument.

Of course, at some time in the future al-Shirri may plan or participate in an attack that targets the US in Yemen, but that has yet to happen, so until it does lets call it what it is: a possibility or even a probability but not a past event.