ITS YAAAA BOOOOOOOY GUZMA!!!!!!
Reading your quotation of the Summerhall passage from TWOIAF revived a thought I had when I read it the first time... The ink blotting Gyldayn's history struck me as a tad convenient for an order that keeps a book called Blood and Fire aka The Death of Dragons locked away in a vault at the heart of the Citadel. I've always wondered if perhaps Egg succeeded, but the maesters were on hand to make sure he didn't. Not that we'll ever find out, but I'm curious as to your thoughts there.