I think they might actually. I've read on here about people having brooks saddles stolen despite locking bolt on post due to undoing the bolt attaching the saddle to the saddlepost. Also, one person said that he once came across a thief undoing the ahead bolt so they could go off with the entire front fork. Both carried out by allen keys.

Also, as someone else said, I think the allen key slots into the pit-key provided with the pitlock pack so it's the actual pit-key slotting into the pitlock bolt and the allen key just acts as a handle/lever to turn it.