You make some good points Rosen, you always do. I don't think the saints are "mediators" and they are not high priests
Matthew 27:52 KJV - obviously, some saints rose from the grave.
Yes, some saints rose from the grave, but they did not rise to immortality and eternal life. They went into the city and were seen by witnesses.
Matthew 27:52-53 KJV
(52) And the graves were opened; and many bodies of the saints which slept arose,
(53) And came out of the graves after his resurrection, and went into the holy city, and appeared unto many.
This would be consistent with other that have been raised to life to this point. The child of the widow raised by Elijah, the daughter of the ruler, and also Lazarus. All these were raised to life, but they were not changed (1 Kings 17:22 ,Matthew 9:25, John 11:44). Paul himself raised one of the saints back to life, and it is understood that he was also raised to a mortal state (Acts 20:10) and would have died again in his normal time.
Proof One
Back to the instance in the gospel account, it does not say that the saints were raised immortal, or that they ascended to heaven, or that they are still alive in any fashion. Actually speaking to the contrary, Paul tells us in Hebrews 11 that the saints of God have not received the promise, and that their reward lies ahead,
that they without us should not be made perfect.
Hebrews 11:39-40 KJV
(39) And these all, having obtained a good report through faith, received not the promise:
(40) God having provided some better thing for us,
that they without us should not be made perfect.
Without an actual scripture stating that these saints that arose
ascended to heaven or
were raised to immortality, I think the more natural interpretation is that they were raised to life in the same fashion as every other person who has been raised to life so far. They would be raised to life in the normal physical sense.
Proof Two
On the topic of being raised to eternal life and immortality, the saints that arose at Christ's crucifixion cannot have ascended to heaven or been raised to immortality. First, Christ only has the special privilege of ascending to heaven (Psalm 24 was used as a proof of the Deity of Christ by Christians as early as the 2nd Century, which specifies that ascending to heaven is the identification of the LORD of Hosts)
Psalms 24:7-10 KJV
(7) Lift up your heads, O ye gates; and be ye lift up, ye everlasting doors; and the King of glory shall come in.
(8) Who is this King of glory? The LORD strong and mighty, the LORD mighty in battle.
(9) Lift up your heads, O ye gates; even lift them up, ye everlasting doors; and the King of glory shall come in.
(10) Who is this King of glory? The LORD of hosts, he is the King of glory. Selah.
... and second, Christ is called the firstfruits of them that slept. If others were raised to eternal life and immortality before Christ, he cannot be the fruitfruits, can he? Someone else would be the firstfruits.
1 Corinthians 15:20-23 KJV
(20)
But now is Christ risen from the dead, and become the firstfruits of them that slept.
(21) For since by man came death, by man came also the resurrection of the dead.
(22) For as in Adam all die, even so in Christ shall all be made alive.
(23)
But every man in his own order: Christ the firstfruits; afterward they that are Christ's at his coming.
So the very gospel (as defined by Paul as being the gospel) says that Christ is the firstfruits of those that slept, which excludes any others. We are also told when others will be raised to eternal life, afterwards at Christ's coming.
So there's actually quite a few good reasons to believe that those saints were raised to life, and died again at a later date.
a) Previous resurrections were to physical life only
b) The scripture does not state that these saints were raised to anything but physical life
c) Ascending to heaven is the identification of God, the LORD of Hosts
d) Christ is the firstfruits of them that slept, therefore he must be first
e) We are specifically told that the saints are not raised to eternal life until after Christ's return.