There's a lot of things I'm willing to suspend my disbelief about when I watch Star Trek. Universal translators, mushroom warp drive, two aliens fucking and making a baby.
One thing I can't accept, though? The idea that the legal definition of mutiny might have shifted over three hundred years and the integration of US law into United Earth law, and then United Earth law into Federation law.
It's not that. It's that mutiny is a particularly heinous crime whose nature is well understood and well documented. Disobeying an order is not mutiny. People disobey orders quite often. Disobeying a direct order is more serious crime which can get you two years. But the order has to be a direct order, and nothing the Captain said remotely met the legal definition of a direct order. If I'm the lawyer my client doesn't serve a day on the lesser charge.
Mutiny is a conspiracy because it has to be a conspiracy of two or more persons. A mutiny of one doesn't even make sense in any reality. Mutiny is the overthrow of the legal chain of command, such as on a ship at sea. One person cannot do that. First officer screams "I'm taking over this ship!" Captain says "No you're not." Helmsman asks "Are you on drugs?" Surface warfare officer says "Is that a frog in your pocket?" Air boss says "You've got some mayo on your chin. No, to the right."
Nobody obeys the first officer because she doesn't have any allies engaged in a conspiracy to take control of the ship. So everyone is against her. A ship or other military unit cannot be run by one person without the consent of other parties. A mutiny can only happen when disgruntled parties get together and formulate a plan to take out the normal command chain in a rebellion against the established authority. One person cannot do this because if everyone stays loyal to the established authority, nobody will obey the commands of the usurping authority. In fact, the usurping authority will get a beat down, be arrested, and be thrown in the brig or stockade because she has no allies. Not one. So all the attempt can legally result in is charges of insubordination, disobedience, or assaulting a superior officer because the crew did not mutiny.
Note that mutiny requires a crew. A crew that includes a subcrew of mutineers. without which mutiny cannot happen because mutiny is a collective crime like lynching or rioting. You can be the only person charged and convicted of lynching or rioting, but you cannot be the only participant. A lynching by one isn't a lynching, it's a murder. A riot of one isn't a riot, it's disorderly conduct and property destruction. A mutiny is like those crimes. It only exists in the plural, not the singular. It is a conspiracy by two or more persons. No matter how brilliant or how evil, one person cannot mutiny without others.
Learn what words mean. Forward you gained knowledge to whoever is writing the show
Wait, that won't help because they've already screwed the pooch by basing the show on something that makes absolutely no sense to anyone who knows anything.