Sorry but you are the one with the strange ideas. My ideas are not strange, they comply with the law.
Yes, your vehicles are private to the extent that someone cannot enter them without permission. But that's as far as that goes. And the government HAS told you to change your registration in the form of a law stating this has to be done within 30 days. You risk fines by not complying with the law.
The management of the complex has the right to make sure that no illegal activity is going on within the complex. The parking lot is private property owned by the complex. An improperly registered vehicle is a violation of the law and they have the right to demand that only legally registered vehicles be parked on their property.
You are way off base here. You are violating the law and that puts in the wrong.