Atrocities are always there, yes. The conquistadores were awful. The point is that they weren't uniquely awful. The stuff they did was not unprecedented, and would have been committed by any European power had they been given the chance, Protestant or Catholic. And the fact that you're using an Oxford book is telling: Anglocentric biases which downplay the Anglosphere's crimes in favor of painting the Spaniards in dark tones are common.
And using diaries from conquistadors or using Hispanocentric sources are not in any way going to paint themselves or the Spanish Empire in a very good light are not biased? The Oxford book used Cortes's own words as well in his letters to Spain detailing his own accounts on the Cholula trickery and massacre. Downplaying the Spainish Empire's atrocities shouldn't be taken lightly. It is a well researched academic book so attacking it just because of its origins and not of its content isn't convincing me.
Anyways the earlier arguments from the first page dealt with how England was or would actually be WORSE than the Spanish Empire so this u-turn on how Spain, England, or any other European would not be different in dealing with the natives of Mesoamerica is quite frankly a bit odd. But nevertheless, my point earlier on my earlier post was that England wouldn't be any WORSE than Spain so my point still stands.
As I said earlier, an English conquest of the Aztecs wouldn't be any different from Spain in their allying of anti-Aztec folks, attacking and committing civilian massacres similarly to the horrible conquistadors, and then capturing Technotitlan with said allies with such brutality on civilians. As detailed in the book, the Spanish were frankly appalled by the human sacrifices of the "barbarians" (as noted by that humanist contemporary 15th/16th century theologian Juan Ginés de Sepúlveda, even he disliked the Mesoamerican practise), and some like him proclaimed their Catholic culture to be superior to these "barbarians".
Whether or not England would be Catholic or Protestant by this time, any English ruler of Mesoamerica would also probably have the same notion as that of Spain's: saw Aztec's mass sacrifices, become appalled by it, and would immediately try to stamp it out and proclaim their culture as superior just like the Spanish. Cortes and his conquistadors burnt books and destroyed indigenous religious idols and temples and stamped out the "sacrificial religion" so the English would probably be doing the same thing to and implement either Catholicism or Protestantism. Like the Spanish, Lake Texcoco and the entire valley as a whole would probably be drained of water and the newly formed New London city would be built in place of the former centres of the Triple Alliance.
As I stated earlier, Spain's and later independent Mexico's indigenous genocides like the Yaquis and Mayans would instead be dealt by the English and their later independent Anglo-Mexican entity (either called New Britain, Meshicko, Columbia, Avalon, Camelot, New Albion, Vesperia, Aurelia, Zephyria after greek air god of the west, idk I like either names).