That’s exactly right. If it’s in their interest to claim responsibility, they will. If it’s not, they won’t. Simple as that.
Per the bomb theory, I’m having trouble reconciling the called-in bomb threat with no evicence of a group claiming responsibility. In other words, I’m wondering why a terrorist group would call in a threat—which would tip their hand—yet not brag about bringing the AF plane down.
The threat was made in Argentina. The downed flight was out of Brazil. The call-in threat could have been a diversion attempt for all we know.
We get ourselves into trouble when we put too much stock in our own ability to think like crazed islamists. I still have trouble reconciling Mohammed Salameh trying to get his deposit back on the Ryder truck he used to blow up the World Trade Center parking garage in 1993... but he did it. It made no sense whatsoever, but he did it.
I don't know why some jihadist would pick up the phone and threaten an Argentine Air France flight two days before he planned on blowing up a Brazilian Air France flight. But I'm not going to dismiss the possibility that he did it just because I can't figure out why.
And I don't get into the claiming responsibility stuff. That's never a consideration for me. Claims can surface days, weeks, months or years after an attack. Sometimes they never come. Sometimes they're not reported right away, sometimes they're not discovered for a while. There is no reliable pattern with these sorts of claims. And there are situations where it's in their interest to make no claim at all (9/11 and the ensuing anthrax attacks being the most obvious examples).
I find the timing of the incident just as compelling a clue as the bomb threat. It's Islam Week. Al Qaeda's shooting its mouth off again. OBL's back with another volume in his Lectures From the Fires of Hell series. Obama is giving an historic speech in the homeland of Ayman al-Zawahiri. There's badness in the air.