They wouldn't let me through the other week because my umbrella had a short metal pointy tip. Even when I pointed out that the metal pen in my pocket that they had no problem with was longer and sharper, the woman (who sounded and looked like a man) grunted and had no answer. I guess it's hard for someone to come up with any rationalisation when their brain hasn't been used in a few years.
These guys and DOTARS need to get a grip on reality.