I am not clutching at straws to prove anything - I am simply stating the fact that despite the Bahai swallowing hook, line and sinker the traditional Islamic tale about how the Qur'an has come down to us completely intact, this cannot possibly be verified and that there is considerable reason to doubt it.
There is no reputable scholar I'm aware of that would seriously advocate the Quran does not reliably represent what Muhammad taught. I provided an example of two scholars Patricia Crone and Michael Cook whose efforts to prove the Qur'an as unreliable was almost universally rejected.
Of course there are degrees of reliability. We would expect variations and changes with oral traditions, small changes in recollections as those are spread throughout a rapidly enlarging empire and then written down in different settings, cultures, languages and dialects.
The Baha'is do not take the Islamic historic view as you say. We simply believe the Qur'an is the 'authentic repository' of God's Word. The rest is a matter for scholars to ascertain.
In fact, according to Shi-ite tradition is it not true that the very person who was responsible for standardizing the text of the Qur'an as we know it today (the 3rd Caliph, Uthman) was himself accused by his fellow Muslims of "changing the Qur'an"?
The Shi'ite and Sunnis both believe the present Qur'an is authentic.
The Shia view of the Qur'an differs from the Sunni view, but the majority of both groups believe that the text is identical. While some Shia disputed the canonical validity of the Uthmanic codex,the Shia Imams always rejected the idea of alteration of Qur'an's text. Only seven Shia scholars have believed in omissions in the Uthmanic codex.
https://en.wikipedia.org/wiki/Shia_view_of_the_Quran
And do we not understand from the same traditions that Uthman ordered the destruction of all Qur'ans that did not conform to the standard text? We therefore know, don't we, that there was, already - just a couple of decades after Muhammad's death - considerable variation among the copies of the Prophet's words that had been made by then (and even more variation among the already growing variety of hadiths) that this was already a major concern for the leaders of the nascent Islamic empire?
I would have thought it was a self evident phenomenon of transmission orally until standardised through Uthman's decree.
And do we not know from the same tradition that this concern was serious enough to lead to the assassination of Uthman himself?
This is an argument used by Christian apologetics. An example of an Islamic response that I don't necessarily agree or disagree with:
http://www.answering-christianity.com/quran/other_books.htm
And do we not know from the same tradition that it was, in fairly large measure, this very concern that brought Muhammad's cousin Ali to power as the 4th Caliph? Ali - presumably being a wise and politically savvy leader - seems to have decided not to interfere too much with the content of the Qur'an and Uthman's standardized text became the one on which future copies were made. But we have no way of knowing the full extent of the various texts that had come about - especially if they were - as the same tradition holds - destroyed during Uthman's Caliphate if they did not conform to the text as approved by his committee.
This is an important point. To support an argument that Uthman corrupted the text you would need definitive statements from Ali to that effect. If Ali is the recognised Caliph and Imam after Uthman and he didn't express any concerns about the Qur'an then both Sunnis and Shi'ites are in agreement as to the authenticity of the Qur'an.
None of this is clutching at straws is it? None of this is my imagination is it? In fact, it is either true, or it is the imagination of the very Shi-ite "historians" of Islam that Baha'is depend on for their understanding of how the received text of the Qur'an came down to us as the intact words of the Prophet Muhammad, isn't it?
Hopefully I've provided further clarification as to what I see as the tenuousness of your position. I'm trying to be fair and can't see any strong case for discounting the authenticity of the Quran.
The paper you provided was useful but needs to put in context of a longstanding and intractably divisive dispute between Christians and Muslims since the seventh century.
Baha'is are not Muslims and we are open to different narratives as to how the Quran came about. Of course we don't think its been corrupted. We don't believe the gospel has been corrupted either and consider the Muslims to be in error when they promulgate such claims.