Supervisor told employee that they were a bad employee because of personality?

If their comment was just based on that person's personality, actions, behavior, etc, then no; however if it was based on a disability, race, gender, age, etc, then it could be viewed as harassment.

That being said, it was not the most tact thing that could of been said. Praise should be done in public, reprimands should be done in private and both should be done in a professional manner.