> it is beyond any reasonable doubt that the non-Muslims had been much better treated under the Arab rulers than the non-Christians were treated after the territory had been reconquered by the Spanish kings.

Yeah, Spain the kingdom didn't really treat Muslims all that great, one just have to look at the "Expulsion of the Moriscos" in 1609 (https://en.wikipedia.org/wiki/Expulsion_of_the_Moriscos). Hard to beat that when it comes to treatment of entire populations.