He did tell her he he informed the RCMP. Whether he gave the details is unknown. He says yes, she says no. The real issue is that he revealed to the public the reason why he canned her. He did not have to do that. He could have left the RCMP deal with that.
If I should fire an employee, I do not tell everyone else that he's been fired, let alone why. If he's committed a crime, I turn it over to the police, but again I leave it to the police to decide whether to announce this. It's not up to me to ruin another person's reputation. the law decides that.
You make some valid points, especially if she is totally lying. If she's not and doesn't have a clue what she's being accused of, I still think (strictly from a common courtesy stand point) Harper should just tell her "you are being canned for sticky fingers in the coffee fund" or whatever the transgression was.