Doesn't look like ebay has banned Seuss. "And to think I saw it on Mulberry st "is listed, bid up to 100 bucks right now. Silly, you can still buy them. The Seuss foundation simply elected not to print new ones. No ban.
Dr. Seuss' estate is who put the six titles on the 'out of publishing' list. I don't own (nor have I read) any of the 'Big Six', but I've got a few others on my bookshelf. I put them between syrup bottle bookends.
