Mine came with Steel nuts. Seriously, new house, steel nuts.
She is "closer" to the truth. The disposal can handle things, but the plumbing past is usually the issue. Grease and oil, or anything greasy/oily. When they cool they coat the pipes. A lot of the time, veggies get caught in the greasy coating and clog the pipes. Long flat runs are the worst.
If she is that worried about things, let her do the dishes!
