"Sovereignity" is just a word. I can also use it to proclaim me and my friends individually "sovereign" so no aggression against them is justified. May you tell me how violence is justified in your eyes when person voluntarily pays for a flight, then pays for a taxi and goes outside the airport without a passport?

Sovereignity is a concept. Whether you want to use this word or another is irrelevant.

As I said in my post the first and mandatory requirement for one to be sovereign is to have a monopoly upon violance within particular geographic region.

What you declare is absolutely irrelevant. You are sovereign if and only if you are firstly capable of defending yoursef from harm and second unleashing harm upon others within this teritory.

There need not be any justification for violence beyond whim of the sovereign. So if you walk outside the airport against sovereigns will, local sovereign may do harm unto you.

And it has absolutely nothing to do with morality.