CIRA International ask with envy; why didnt Allah protect the bible from corruption?

In answer to the video "Yusuf 12:111 - The Quran Affirms the Bible"

The discontinuation of the line of prophethood is among the reasons that necessitated the protection of the final revelation to mankind, a revelation containing all previous books 98:2-3 as here reflected in the declaration of faith

2:177"believe in Allah and the last day and the angels and the Book and the prophets".  

3:23,5:44,4:44,51"Have you not considered those to whom a portion of the Book has been given? They buy error and desire that you should go astray from the way".

This indicates that the Torah and Injil were not the final words of God, but portions of one Book 6:156. The Quran in fact uses that established pattern of continuous revelation, to comfort the prophet, telling him that should his adressees disbelieve in that same pattern that is now bestowed upon him, then let him now, people preceded him that wholeheartedly believed in it. Further, their rejection does not compromise the honor and credibility of that lofty institution of prophethood. Instead of grieving, or even doubting, the prophet should follow the guidance of his predecessors who held fast by the revelation that came to them 6:84-90. All previous revelations are part of one Book called the Mother of the Book/umm al kitab which the Quran is also part of

43:4,13:39,2:236"and remember Allah's favour to you, and that which He has revealed to you of the Book".

The previous revelations forecasted the final revelation in the form of the Quran 4:47. This draws attention to an important truth: all the revealed scriptures contain the same spiritual and moral principles. They cannot contradict eachother and their only differences reside in that they were made to conform to the language of the addressees

26:192-6"And most surely this is a revelation from the Lord of the worlds. The Faithful Spirit has descended with it, Upon your heart that you may be of the warners, In plain Arabic language. And most surely the same is in the scriptures of the ancients".

The Quran then verifies the truth of these divine portions of the one Book and offers a clear global explanation of it

12:111,10:37,20:133"Has not there come to them a clear evidence of what is in the previous books?".

This is why it is said to be the Guardian and Arbitrer/Muhaymin and a clear explanation of THE Book (singular) of which past scriptures including the Quran are part of 5:48-9,10:37. This single scripture containing all past revelations as well as the Quran is said to be highly secure, purified and preserved, exalted and honored, inaccessible to evil interference and only between the hands of the most honourable custodians 26:193,56:77-80,80:13-16,81:19-21,88:22. It has been engraved in the lawh mahfuz/the preserved tablet 85:21-2, hence it being referred to in the opening verses of sura baqara as it is dhaalika al kitab/that book or writing, denoting distance through the pronoun, because its katb/writing is done in a far heavenly place.

In contrast the Quran speaks of this/hadha al Quran denoting closeness because its recitation is being done in this world. Another instance of the Quran's surgical use of words. 

The Quran, being from the same God and containing the same basic wisdom and truths of ancient scriptures 6:91,26:196,29:46 speaks highly about the Torah and Injeel. They are referred to as sources of mercy, wisdom, guidance and light 5:43,44,46,7:154,11:17,28:43,46:12 as well as criterions of truth and falsehood (furqan) clarifying all things 2:53,21:48,28:43,37:117. 

It even cites them sometimes as sources of guidance hand in hand with the Quran 28:48-9. Because again, they are never said to be totally corrupted. Read with the knowledge of the Quran, whose function is to be the muhaymin/protector and arbitrer, one can discern the guiding parts of previous oral and written traditions from the portion that were corrupted, either purposefully or through neglect.

 In 46:12 it says the Torah came prior to the Quran, as a guide and mercy. It is this guiding and merciful aspect of the Torah that the statement musaddiqan/declaring true, refers to, not simply the Torah. It doesnt say declaring "it" true. This is seen by the rest of the verse, paralelling the guidance and mercy of the Torah with the Quran being a warner and giver of glad tidings. Again we see, the Quran only confirms the truthful aspects of past oral and written traditions, which the Quran never claims were entirely blotted out. This restricted aspect of the Quran's confirmation of the Torah is made clear in 6:154-7. 

The passage starts again with a praise of the Torah as being a book of mercy and guidance, followed by a parallel statement about the Quran, echoing stricly the merciful and guiding aspect of the Torah

"And this is a Book We have revealed, blessed; therefore follow it and be God-conscious that mercy may be shown to you".

The Torah contains many things that are neither guiding, nor sources of mercy, and other things that erroneous or even outright blasphemous about God and His prophets. The Quran does not confirm these things, and sometimes openly rejects them.