"Standard statement" would mean whenever there is no particular reason to believe that something was intentional, right?
Would you prefer that the FBI said that *everything* was terrorism, unless proved otherwise? Would that be helpful or valuable in some way?
See, the thing with terrorists is... they like to do things that leave no doubt. They want the big show, with their credit.
Stuff falling down on its own just isn't their style.
You mean like they DIDN'T do with 9/11?
Or perhaps that attack wasn't big enough to merit the effort to stake their claim to fame?
While it's true that OBL did fess up to it, I seem to recall the venue being a private tete-a-tete (a scumbag to scumbag tea), which was videotaped for posterity (rather than distribution). IIRC, the tape was found in a safe house our guys knocked over.
This was a year or two after the fact.
It wasn't until well after that inadvertent release that they openly took credit for the attack.
But, maybe you're right. Maybe 9/11 just wasn't a big enough deal for them to care one way or the other about taking credit for. That must be the case, if your logic holds any water at all.