This verse focuses on the concealment of scripture rather than its ontological corruption.
Surah 2:174:
Indeed, they who conceal what Allah has sent down of the Book and exchange it for a small price - those consume not into their bellies except the Fire. And Allah will not speak to them on the Day of Resurrection, nor will He purify them. And they will have a painful punishment."
To "conceal" something, that thing must physically or intellectually exist.
If the Jews and Christians of Muhammad’s time were concealing (kitman) the "true" Torah and Gospel, it implies that the textual corruption (tahrif) often claimed by modern Muslims had not actually happened yet.
If it was there to be hidden in 610 AD, we can compare it to the manuscripts we have today (like Codex Sinaiticus), which match Christian's current Bible.
If the Quran commands the "People of the Book" to stand by their scriptures (as seen in Surah 5:47 or, 5:68) and warns them against hiding parts of it in 2:174, it validates the Bible as a source of truth.
The dilemma then arises because the Bible (which the Quran here protects from concealment) explicitly contradicts the Quran on the deity of Christ and the Crucifixion.
The threat of "Fire" for those who conceal the Book suggests that the audience had the agency to reveal the truth. If the text were already corrupted beyond recognition, concealment would be a moot point.
This reinforces the polemic argument that the Quran views the Bible as a valid, extant authority during the time of the Islamic revelation.
How would you like to bridge this specific verse with the "Clear Proof" arguments found later in the Surah?