I was at Gatwick airport once and I stumbled upon a similar farce:
I presented my hand-luggage for inspection and was told that my toothpaste must be in a re-sealable plastic bag.
This is roughly how the conversation went:
Security Bloke: This must be in a re-sealable plastic bag.
Me: Oh, I didn't collect one on the way through.
Security Bloke: Then I can't let you take it on board.
Me: Ah, the stack of bags is just back there (pointing to the security gate behind me) can I go and get one?
Security Bloke: No, once you've come this far, you can't go back.
Me: (Spotting a few of them lying around on the shelves from where the security bloke was serving) Oh look, there are some right next to you, could I have one of those please?
Security Idiot: No, sorry - I cant let you have one.
Me: But they are the same regulation re-sealable bags as those ones back there?
Security Bloke: Yes.
Me: Well, why can't I have one of those? they're right there next to you!!
Security Moron: It's against regulations for me to give you one of those.
Me: But they're the SAME ONES as the ones supplied back there!!!
Security Idiot: Yes, I know, it's against the rules for me to hand you one.
Me: Why?
Security Totally Stupid Dogmatic Git: Because it's against the rules.
Me: You've already told me that, WHY is it "against the rules"?
Security TSDG: Because it's against the rules.
Me: Ok, so it comes down to just plain dogma then?
Security TSDG: (silence)