Firstly, as people like Bruce Schneier point out again and again, terrorists are neither waiting for an accidental opportunity, nor do they take the risks involved in such an opportunity. They don't sit around waiting for a diversion and certainly not for a diversion that leaves a considerable chance to get caught.
Secondly, if the judge was right, airport security would be so broken it's not even funny. If he's right, terrorists can easily get a bomb on board: they only need someone to stage a fake protest, which is enough to divert the security people. Luckily, it isn't that easy.
This judge has insufficiently thought this through. He has the security of a school or cinema in mind, where some thief or other opportunist might sneak in when someone distracts the guard.