Bin Laden's tape before 2004 was a denunciation of Bush - but it's plausibly suggested here, on the basis supposedly of CIA informants, that this would have been an attempt to help ensure a Bush victory, with Bush being seeing as the kind of opponent al Qaeda would prefer to be dealing with.

On that basis for Al Qaeda to endorse McCain would on the face of it be a way of damaging his prospects. Except that, if that is what people assume to be the case, the effect of the endorsement would in fact be the reverse, a way of helping him, with Obama being seen as a more dangerous enemy...

There's an infinite regression of bluffs and counter-bluffs and counter-counter-bluffs. Best not to take any notice at all of anything Al Qaeda says about these matters.