Is this legal for the company to go against a doctors decision in the state of Indiana? A doctor's note has no force of law. Frankly, doctor's notes are a dime a dozen (you can even get them on the internet these days) and your employer has no obligation to excuse absences because an employeee presented them with a doctor's note unless the situation qualifies for leave under the FMLA.
or...... Is this legal for them to fire you if you have a doctors slip? Yes.
A person, who is nice to you, but rude to a waiter, is not a nice person. (This is very important. Pay attention. It never fails.)