> proof that he, himself is conscious.

Unstated (or very understated) in the scene is the fact that a human demonstrably acts and functions within the social context, having a constant awareness of risk and accountability ("skin in the game").

A human of mature age is entrusted with responsibilities and accountability for consequences. Insofar as responsibility for consequences is borne, a human may be considered responsibly conscious in behaviour. (Criminal behaviour is defective.)

A technology may also someday be entrusted with responsibilities and accountability for consequences. But there is as yet no such technology.