in fact, it's standard revisionist nonsense - what they teach you nowadays is that arabs didn't conquer the region, so much as they migrated into it. that change in mindset actually isn't obscure, anymore. nobody teaches the standard "islam conquered via the sword" thing anymore, except to debunk it.
as usual, the truth doesn't lie in any specific caricature of peaceful caravans or bloodthirsty conquerors, so much as it is something in between. you have to understand the roman-persian conflict (an ancient war, that goes back to thermopylae) to understand the arab expansion, and that is difficult because the destructiveness of it set in a dark age that the rise of islam exists within. your own critical thinking skills aside, this is a period where the world's two largest and most advanced civilizations fought themselves to bloody pulps, and both caved in on themselves. islam only emerges, historically, in the wreckage of this - and as a consequence of the simultaneous collapse of these two major civilizations.
so, the story is that the muslims drove the romans out of the middle east, but if you understand the history then you know this doesn't add up because the romans had already been driven out by the persians, who were aided by a semitic revolt. what happened a few decades before the supposed life of muhammad - and this is real history, however obscured - is that there were major revolts in egypt and the levant over a type of christianity that was considered different than the type practiced in constantinople, and the persians took advantage of it by offering the heretics military support. so, there was an alliance between the heretics in the region (who were numerically dominant) and the persians (who were the sworn enemy of the greeks, and therefore of the greco-roman byzantines). it is in fact well understood that heraclius had to make some concessions to stop them from breaking off, and that those concessions would have included enough autonomy to avoid these sorts of conflicts.
the details of the exact relationship between constantinople and the heretic bishops in the semitic speaking regions will no doubt be forever shrouded in the dark age they occurred within, but nobody doubts that the conversion to islam was inextricably linked to the christian infighting that was taking place, that there was some concept of pan-semitism and anti-roman sentiment underlying it and that the arabs could not have held the region without the active support of the semitic christians living there at the time.
once you realize that the story that was told was at best an exaggeration, the jump to complete fiction is a matter of degree. is most of it true, some of it true, almost none of it true or absolutely none of it true? and, the fact is that if you insist on a purely evidentiary approach, there's essentially no evidence for any of it, and quite a bit of evidence that almost all of it is flawed.
...but i would claim this isn't even necessary, as when something reads off as fictional bullshit, it probably is. it simply doesn't get past my bullshit detector, and it never did.