Nope, that's wrong.

BusinessBot Bob knows the answers when it comes to Amazon Royalties!
Amazon offers two main royalty rates, the 70% option and the 35% option. The 70% option is only available to you if your book is priced between $2.99 and $9.99, and has nothing to do with exclusivity. The 35% rate is required if you are publishing your book either below $2.99 or above $9.99, and some other limitations apply (primarily dealing with the size of your eBook file). Also, the locale of the buyer plays into it—for example, typically, when a book is sold in Mexico, it's only eligible for the 35% royalty.
There are some other considerations, like delivery fees, the size of your book, and so on. You should read up on the details of these royalty programs at the extensive and great Amazon Help pages. The article dealing with royalties starts here: Amazon's Help Pages about Royalties . Once you get to that page, in "Step 1," under "eBook pricing," there's another link, "Learn More about eBook Royalty Options." That takes you to this page, which tells you everything you ever wanted to know about Amazon Royalties. It's your money—so make sure you read these small articles, to be fully informed.
Who Would Choose 35%? Why Would They Do That?
Some authors who have very large, image-dense books, like coffee table books, will decide to opt-in for the 35% royalty, because that royalty rate does not pay delivery fees. A "delivery fee" is a $0.15 (Fifteen Cents) per megabyte fee that Amazon charges, to deliver your book to a customer, each time it is purchased. The larger a book, the larger a delivery fee would be. This delivery fee only applies to books in that 70% royalty program.
The "Kindle Select" program is the marketing program that requires exclusivity. This program has a number of options that you can choose, underneath it—either making your book completely free, for any 5 days out of 90, or joining the Kindle Prime program, where Amazon Prime customers can borrow books each month (as an author, you get paid a prorated per-page fee for each page read), and so on. You should read up on these programs here: Promote Your Book at Amazon which will explain those programs to you. However, joining the program has no bearing whatsoever on your royalties or for which rate you are eligible.