Sorry, but until I get a clarification from Apple, I disagree. The license states that you may install it on all your Macs. Highly unlikely that a single user would have more than 5 or 10 of course, but, if they did, they should be able to.
If the only relevant term was the one you highlighted, then why would it contain the other verbiage? And why would kb article 4854 state that you can install it on all of your computers without an appropriate disclaimer pointing to the iTunes terms?
FWIW, I've read the entire iTunes/MAS/etc terms as well as the SLA's. I will call Applecare when I have time to question this point; however, throughout the past year, the standard answer has always been "all" computers you own and control and not limited to a certain number.
Addendum: the relevant difference may be the fact that we are discussing an operating system, not an "app", which is something I will mention when discussing it with Apple. I cannot find any mention of OS purchases in the Mac App Store terms (subheader of iTunes terms).
Second Addendum: Excerpt from iTunes/Mac App Store terms:
LICENSE OF MAC APP STORE AND APP STORE PRODUCTS
The software products made available through the Mac App Store and App Store (collectively, the “App Store Products”) are licensed, not sold, to you. There are two (2) categories of App Store Products, as follows: ℹ those App Store Products that have been developed, and are licensed to you, by Apple ( “Apple Products”); and (ii) those App Store Products that have been developed, and are licensed to you, by a third-party developer ( “Third-Party Products”). The category of a particular App Store Product (Apple Product or Third-Party Product) is identified on the Mac App Store application or App Store application.
Your license to each App Store Product is subject to the Licensed Application End User License Agreement set forth below, and you agree that such terms will apply unless the App Store Product is covered by a valid end user license agreement entered into between you and the licensor of that App Store Product (the “Application Provider”), in which case the Application Provider’s end user license agreement will apply to that App Store Product. The Application Provider reserves all rights in and to the App Store Product not expressly granted to you.
You acknowledge that the license to each Apple Product that you obtain through the App Store Services, as defined below, is a binding agreement between you and Apple. You acknowledge that: you are acquiring the license to each Third-Party Product from the Application Provider; Apple is acting as agent for the Application Provider in providing each such Third-Party Product to you; and Apple is not a party to the license between you and the Application Provider with respect to that Third-Party Product. The Application Provider of each Third-Party Product is solely responsible for that Third-Party Product, the content therein, any warranties to the extent that such warranties have not been disclaimed, and any claims that you or any other party may have relating to that Third-Party Product.
You acknowledge and agree that Apple and its subsidiaries are third-party beneficiaries of the Licensed Application End User License Agreement or the Application Provider’s end user license agreement, as the case may be, for each Third-Party Product. You also agree that, upon your acceptance of the terms and conditions of the license to any such Third-Party Product, Apple will have the right (and will be deemed to have accepted the right) to enforce such license against you as a third-party beneficiary thereof.
And, scrolling further:
MAC APP STORE PRODUCT USAGE RULES
Except as otherwise set forth herein,
ℹ If you are an individual acting in your personal capacity, you may download and use an application from the Mac App Store (“Mac App Store Product”) for personal, non-commercial use on any Apple-branded products running Mac OS X (“Mac Computer”) that you own or control.
and
APP STORE PRODUCT USAGE RULES
ℹ If you are an individual acting in your personal capacity, you may download and sync an App Store Product for personal, noncommercial use on any iOS Device you own or control.
I believe there is no need for me to check with Apple?