Pottermore revealed that Minerva McGonagall's father was a Presbyterian minister, who kinda freaked out when he learned about magic. McGonagall in canon, therefore, was raised knowing perfectly well about Muggles; she wasn't a pureblood raised in the wizard world as MoR depicts.

So what I meant was that given that there's absolutely no way to write himself out of getting McGonagall's backstory wrong, I am perfectly content for Eliezer to not attempt to write himself out of this far subtler discrepancy from reality.