Surprisingly that quote from the Armenian site didn't strick me as odd at all.
I mean Christ is one person, not two, he was 100% divine then he became human in the womb of the Theotokos, andd became 100% God and 100% man.
That is what the site is saying from my understanding...but I could be way off base....
just my opinion....
Hypostasis is not synonymous with prosopon/person. Hypostasis stands for an individual instance of an ousia/essence.
Christ is one Divine person. He is always a Divine person - the eternal Word of God. This divine person has united a real individual instance of humanity, complete in every way, at the moment of the incarnation, but He is still the Word of God who is now incarnate. He is human but he is not a human person, that would mean that there were two persons in Christ. There are not.
St Severus explains that there are self-subsistent hypostases and non-self-subsistent hypostases. The humanity of Christ is complete in every way but it does not exist on its own or for itself. It exists only in union with the divinity of Christ, which does exist on its own and for itself, having its own Divine person - the Word of God.
In the incarnation the Divine Word of God owns both His divinity and in the economy of our salvation he also owns his own humanity. But the person, the one who owns, is the Divine Word, not a human person. This is the wonder. The Word of God has become flesh. But He is still the Word of God, as a person, even though he is completely and perfectly human according to the humanity which he made his own.
So the Armenian site is quite correct.
It does not say that there is only a Divine hypostasis, because in Christ there is now also a humanity which is hypostatic, but one which is not independent or separate, it is not a self-subsistent hypostasis but it is real, one which only has any existence at all because it belongs to the Word and is united inseparably to his divinity.
As the later Eastern Orthodox came to describe it, the humanity is enhypostasised in the divine hypostasis. It becomes an individual by union with the person of the Word of God. It isn't an individual on its own. We don't confess God the Word and Christ the man, but Christ the God-man, without ever suggesting that either the humanity or divinity are confused or mixed.
But Christ is God the Word.
"The Word became flesh and dwelt among us"
Nestorianism was defective because it taught that in Christ there were two self-subsistent hypostases or individuals, which St Severus says have their own person imprinted on them. This cannot but mean that there was God the Word and Christ the man whatever attempts are then made to unite them. Perhaps it is slightly paradoxical but the Divine person became human without becoming a human person, he became human though. "Emmanuel".
Seeking your prayers