I understand your point, but let me ask...does this mean that the vast majority of non-violent/peaceful Muslims are under the impression that the history of Muhammad is inaccurate and/or they ignore it and/or they justify it and/or...they don't entirely believe that the Qur'an is the eternal word of God?
A combination of those, far as I can tell. From what I have seen:
1. There is a measure of creative emphasis and reassuring assumptions going around. "There is no compulsion in religion" is supposed to trump more violent verses, and those must be justified by the supposedly unreasonable oppression of their neighbors.
In other words, it is taken for granted that Islam / the Quran / Muhammad
must be always holy and fully justified, accurate and true, and any appearances to the contrary can only be ever met due to dishonest representation, corruption of the texts (and this one is not even applicable to the Quran except when translated) or unreasonable pressure from malicious "outsiders". There is even considerable, consistent recurrence of suggestions that badly behaving Muslims must be secretly blasphemous atheists or something else just as unholy.
2. Many Muslims end up hiding behind scripture. It is not at all unusual for whole passages of the Quran to be presented in lieu of actual personal statements. At times it is difficult to avoid the impression that the Quran becomes an actual shield against the unconfortable duty of justifying one's stances. Particularly when Al-Baqara 256 is raised, often very much at odds with whatever else the devotee says.
3. I wonder how many Muslims even seriously question whether the Quran is or could possibly be literally true and immutable. The cultural taboo against questioning it seems to be very deep indeed. I don't doubt that many Muslims simply find the idea of truly questioning it too odd to pursue, and too scandalous to seriously consider.
My sincere impression is that the completeness and infalibility of the Quran has at this point become a social icebreaker of sorts, a safe subject to mention in most any situation among Muslims to cause a reassuring sense of agreement when such reassurance is needed. But whether it actually means anything, or how often, is not at all clear. Many may simply find it far too much trouble to raise the question and end up reproducing the attitude out of rote learning and the need for clear social roles.
That would also explain a lot of their relutance to actually deal at any length with stinking non-Muslim kaffirs that keep raising inconvenient subject matters and failing to pursue the many opportunities of demonstrating proper etiquette and submission towards the lifeblood of their way of seeing the world.