The hooligan in me says that if I'm knicking a bike and a bit stuck to the seatpost starts squawking at me then I'll hit it with a hammer hard. That'll probably sort out the siren and the tracker in double quick time...
The other thing is the mounting: useless for a dropper seat post and, as I know from expensive experience, mounting a light that sticks out from the bit of the dropper post that extends from the seat post tube makes a nasty noise and a hell of a mess when the suspension fully compresses on a hard landing. ?