On eBay, you can presently buy "Mein Kampf." You can presently buy a number of books by Louis Farrakhan. You can buy Salman Rushdie's "Satanic Verses," a book so offensive to the Muslim community that a fatwa was issued on him.
But allegedly you cannot buy one of the six Dr. Seuss books that were recently announced to be racist and problematic, because eBay will remove the listing under its "offensive content" policy.
EDIT: The books seem to be available for sale on the US and UK eBay sites, so perhaps this is someone acting without authority at eBay?