There are mountains and mountains of literature about a great deal of things, no one human can be expected to be aware of them all.
Since that is obviously true, the lack of awareness about a single topic isn’t “ignorance” - it’s not like PG studiously ignored all of that literature. More likely he just never came across it, so the more apt word is “unaware” rather than “ignorant”.
To criticize someone merely for pondering about a subject they aren’t well-versed in is hostile gatekeeping. I think those who are educated in the relevant subject would do well to be more welcoming and informative to newcomers.