I was flying into Ben Gurion airport when the 9/11 attacks happened. When I landed, I saw the televisions with coverage and muslims watching, smiling, high-fiving. So, there is no disproving something I witnessed, in person.
That kind of reminds me of the incident where the Israeli 'art students' or whatever were rounded up in New York after a lady reported them high-five'ing and taking photos of the smoking twin towers on 9/11 with a lighter held under it.
My personal belief is that this incident does not necessarily implicate Israel, and maybe not even these particular Israeli's who may have been fictitious. If I were designing the operation I would have been most concerned about the follow-up in the media. To thwart unwanted investigation, I would have made things be fairly clear to various editorial staffs where an exploration may end up. I don't think it is particularly arguable that Jews are over-represented in the U.S. media, nor that Jews tend to have a propensity to not wish to see misfortune befall that state..and being implicated or framed would qualify as misfortune since much of Israel's national security is predicated on exploiting the U.S. and we still have enough of a democracy to where this would do damage. For this reason I believe it would be (and was) an effective strategy to discourage very much real journalism around the event in mainstreamland.