It did not change. The father used human form like that of Melchedik in a vision or a dream . Moses' body and Elijah long gone.
Moses to represent the letter of the law death .was not allowed in the promised land. A parable to help us understand the law that kill. It will not be part of the new order.
The Father was simply protecting the integrity of sola scriptura .All things written in the law and the prophets. Therefore using Moses the law giver (death) and Elijah to represent the prophets (the law of faith) together making a perfect law as his witness to us. The just (Moses the letter). and the justifier the prophets typified b Elijah .
Romans 3:26 To declare, I say, at this time his righteousness: that he might be just, and the justifier of him which believeth in Jesus.
The same two witnesses of God used in Revelation that will be silenced for a short period .
The same two witnesses that protected the integrity of the work Moses and Elijah the parable of Luke 16.
In that parable (Luke 16) of "two teaching masters". Unbelief is displayed as those who seek after the
dead .Like with Catholisicim(3500 patron saints. ) necromancy.
No matter how many times Jesus corrected him he walked away in unbelief. (no faith) He would be like Peter who struggled to walk by faith as a claim of fame said : Build a shrine . Hoping looking that corrupted flesh and blood could profit for something.
Then he said, I pray thee therefore, father, that thou wouldest send him to my father's house:For I have five brethren; that he may testify unto them, lest they also come into this place of torment. Abraham saith unto him, They have Moses and the prophets; let them hear them. And he said, Nay, father Abraham: but if one went unto them from the dead, they will repent. And he said unto him, If they hear not Moses and the prophets, neither will they be persuaded, though one rose from the dead. Luke 16: 27-31
Faith comes by hearing the understanding of God. not literally seeing .No faith needed to see. Then the reward is seen . .No living hope (faith)
Luke 24:27 And beginning at Moses and all the prophets, he expounded unto them in all the scriptures the things concerning himself.
Luke 24:44
And he said unto them, These are the words which I spake unto you, while I was yet with you, that all things must be fulfilled, which were written in the law of Moses, and in the prophets, and in the psalms, concerning me.
The two witnesses Moses and the prophets
Revelation 11:3 And I will give power unto my two witnesses, and they shall prophesy a thousand two hundred and threescore days, clothed in sackcloth.