Matatics is mixing up liceity and validity with regard to the Sacraments.
Not only that, he is completely confused about liceity.
It is at the level of common sense, as Ladislaus says, but all the principles have been established by the Church - you can use rigorous logic to arrive at the necessary conclusion.
The supreme law of the Church is the salvation of souls.
The Church's Canon Law anticipates situations where the letter of the law may work against the spirit and purpose of the law.
Supplied jurisdiction is real jurisdiction.
As St Thomas says, in times of necessity there is no law!
A state of necessity justifies the law of necessity which justifies all means necessary to continue the mission of the Church.