First of all, for books that are entertainment (most fiction), how is this any different from series that are exclusive to Netflix? The answer given by the author is a non-answer, claiming you can "buy DVD's online". Yeah right, please show me where I can buy Tiger King on DVD? I didn't think so.
Second, for books that are more in line with libraries' missions to make information accessible for an educated citizenry, the original print and ebooks are still available, right? And if you have vision impairment, there are also methods for automated screenreading, since most books don't have audiobook versions.
So I don't really see any valid complaint here except "we want to sell things exclusive to other stores" which, yeah, and I'd like to have a billion dollars.
If you want to have the conversation that there should be laws breaking up creation and distribution and making exclusive distribution illegal, then go ahead, but that would shake up everything, a pretty radical change. But if you're not going to go there, then there's no reason why audiobooks shouldn't be exclusive while other things get to be.