This book looks interesting, but it's unfortunate that there's no way to get the instructor's book for the answers to the exercises. Sort of diminishes the value of the book for self-learners.
But it would appear that you're correct that Pearson doesn't seem interested in selling the 3rd edition solution manual to anyone that isn't an instructor [1]. IMO, fuck their antiquated gate-keeping bullshit.
[0] https://dreamanddead.gitbooks.io/csapp-3e-solutions/content/
[1] https://www.pearson.com/us/higher-education/product/Bryant-I...