This is an incorrect definition of a signal.
I agree that intention is irrelevant. But a powerful person blending in with their dress isn’t actually sending a signal. There is nothing to perceive because they look like everyone else.
The signal is only in if they’re recognized. Your definition of signal is congruous with any trait someone thinks a powerful person has whether it’s real or imagined.
Yup. Camouflage isn’t a signal.