So, Amazon is paying the publisher the wholesale price regardless. Amazon's discounts cut into Amazon's profits, not the publishers -- or even result in Amazon taking a loss.
I think this publisher quoted has to tell us why he "needs" the price on Amazon to be a certain amount, when it does not effect how much he gets paid per copy -- the initial naive interpretation would be that if Amazon wants to cut their profits, so presumably more copies sell, while the publisher is still making the same amount per copy -- this would be good for the publisher, no?
It is a weird market (with Amazon appearing to routinely sell books at a loss), and is dominated by Amazon, which indeed isn't great for a healthy diverse bookselling market.
But publishers are saying some weird stuff, without explaining themselves.