T-shirt with picture of armed robot endangers British aviation system

This poor guy tried to board a BA flight at Heathrow terminal 5 but was turned back and told to change out of his t-shirt, which featured a Transformer robot carrying a gun -- a robot with a gun that apparently posed a threat to flight safety.

Go through security, get pulled to the side. I'm wearing a French Connection Transformers t-shirt. Bloke starts joking with me is that Megatron. Then he explains that since Megatron is holding a gun, I'm not allowed to fly. WTF? It's a 40 foot tall cartoon robot with a gun as an arm. There is no way this shirt is offensive in any way, and what I'm going to use the shirt to pretend I have a gun?
Link (Thanks, PT!)