Fired for break time

What is the name of your state?What is the name of your state? Michigan

My sister has worked for a company for 12 years and has a good work record. They get a half hour lunch and 2 15 minute breaks. My sister never takes her breaks in the morning or afternoon but has taken then with her lunch time for a total of an hour. On her time card she wrote 30 minutes and counted the other half hour as her 2 15 minute breaks.
They fired her for this. Is this acceptable? She has been a loyal employee for all these years and now they fire her for that? Just doesn't make sense.
They do not have a union.

Whether it makes sense or not, it is legal.

Breaks are not mandatory under either Federal or Michigan law. (Michigan requires breaks for minors but if she has been with them for 12 years she is clearly not a minor.) The company is not obligated to allow her to take any breaks at all, and they can dictate when and how she takes them. If they do not want her to take an hour lunch and no breaks, they don't have to allow it, and they can fire her for doing so. It is not her perogative to decide when to take her breaks; it is theirs.