"Thousands of books go out of print every year, so what's the problem with us banning these specific books for political reasons?"

"Does it really matter that we banned these dozens of books? Thousands others were not banned, and are available to the Soviet reader at the nearest bookstores!"

This is a slipper slope, and we're already sliding quite deeply into it. Amazon just banned a book about transgenderism that it considered "offensive":

https://ncac.org/news/amazon-book-removal

This is clearly the Soviet case: it's not banning a single book, it's banning the ideas that it presents, for being Politically Incorrect. Once the book is unavailable, American readers will not have access to these ideas anywhere. Any other book presenting these same ideas will also be banned on the same grounds.

This is precisely what was happening in the Soviet Union and similar totalitarian regimes that banned "forbidden / politically-incorrect" ideas.