I look at whether it's actually moving or not. There's enough cars on the road with their brakes and indicators wired up the wrong way round (or not at all, which is always good for a laugh) for me to distrust such ephemeral indications of movement or not.

And FWIW, the advanced motoring groups in the UK advocate handbrake/neutral whilst waiting in traffic, without exception, on the basis of safety (if you get rear-ended, you want the handbrake on to hold the car where it is - the footbrake may kick up, you won't have your foot full on it (because no-one ever does except in an emergency and not even then, hence EBA in Mercedes and other cars) and doesn't hold the rear wheels as hard, and the drive-train disconnected to save damage to the engine) and courtesy (people with normal eyesight get dazzled by high level brake lights).

So no, it's not an odd idea at all.