That is not what anyone has said.
Of course you are entitled to stand up for your rights and the rights of your wife. But you need bear the limitations in mind.
If you buy a new television which breaks down when you take it home, you are entitled to exercise your rights and take it back to the store and have them fix it or replace it. You are not entitled to take it back to the store and punch the shop assistant in the face for selling you a dodgy television. You are not entitled to go back to the store at midnight, break through the door and take a new one.
The same applies on a plane. If someone has taken your seat, you are entitled to complain. You are entitled to follow the matter up with the cabin crew, or subsequently with the airline. You are entitled to pursue remedies (if any) available under the terms of your contract with the airline (for example if you have paid extra for a seat). Or you might ask the airline for a goodwill gesture for your inconvenience.
You are not entitled to manhandle the person sitting in your seat.
The law no longer recognises a 'sense of honour' in the terms you describe. No longer can we challenge someone to a dual at sunrise.
Your responses and conduct on board must, at all times, be lawful. If they are not, you potentially become the problem, and the airline is entitled to off-load you both by law, and under the terms of the contract you have with the airline.