This seems a semantic carving of the discussion to match the argument though.
> Person 1: Just stop it. Want harder.
> Person 2: I can't.
> Person 1: Well, you have an addiction then, not just a bad habit; my point was about habits.
If we grant this: then the great-grandparent's response fails to inform us of anything beyond merely how we choose to define words. The advice works until it doesn't, which is tautologically true but not useful.