Great question - a question that would start a debate about the validity of copyright law, a debate which goes back centuries, and a debate where I can see both sides. But nobody is having this debate - they seem to be just taking one side, the side opposite the one hundreds of years legal scholars have taken.

if amazon pushed hard enough / paid some money out then they would have been able to convince the publishers to allow the bought books to, stay bought

Absolutely, they could also push hard enough/pay enough money and only allow material onto the Kindle if copyright owners allow customers to make copies and derivative works of their books. But why should they?

but even so, 1. I dont see what the length of time to start reading has to do with anything.

2. why should they? because they are a company who needs to serve their customers interests or they will go out of business, thats a pretty compelling reason in my opinion.

Well, in this case, they have two sets of customers - publishers and readers. Congress debated and decided that authors have certain rights - the right to sell copyrighted work with protection from copying, production of derivative works, performance, etc.

In particular, it includes the right to withdraw sold books.

How exactly should Amazon decide which of these rights are "moral" or "immoral", and take them away from one set of customers for the sake of the perceived rights of another set.

you seem to be confusing permissible with law with the right way for a company to act, whay they did may have been legal, but it was very very obviously wrong, they understand that, everyone else does.

changing the laws to be somewhat sensible would obviously be a better solution, but amazon doesnt have that luxury, so they should strive to be making the best judgement decisions they can.