Flagrant foul for number change?

[Sharpshooternes]

This seems like an excessive penalty for not reporting a number change to the scorer and an official. I can see a player who had blood on a uniform changing uniforms and neglect to inform anyone after the change, most likely from ignorance from the rule not in effort to deceive the officials. Not that I am excusing ignorance but has anyone had any experience with enforcing this rule and how did you handle the coach who went ape s@!# crazy when his leading scorer gets tossed for this?

It also states that they must inform the scorer AND the official. How does this procedure usually work? Dead ball, when they sub in, at the time of the change?