Please note that this agreement allows us to remove applications from your Windows 8 Beta enabled device in certain circumstances. See the Can Microsoft remove apps or data from my device? section below for more details.
And then in a section specific to app and data removal:
Can Microsoft remove apps or data from my device? We may change or discontinue certain apps or content offered in the Windows Store at any time, for any reason. Sometimes, we do so to respond to legal or contractual requirements. In cases where your security is at risk, or where we’re required to do so for legal reasons, you may not be able to run apps or access content that you previously acquired or purchased a license for. In cases where we remove a paid app from your Windows 8 Beta device not at your direction, we may refund to you the amount you paid for the license. Some apps may also stop working if you update or change your Windows 8 Beta device, or if you attempt to use those apps on a Windows 8 Beta device with different features or processor type. You are responsible for backing up the data that you store in apps that you acquire via the Windows Store, including content you upload using those apps. If the Windows Store, an app, or any content is changed or discontinued, your data could be deleted or you may not be able to retrieve data you have stored. We have no obligation to return data to you. If sign in information or other data is stored with an expiration date, we may also delete the data as of that date.
From a security point of view, this makes sense. Both Apple and Google have 'kill switches' built into their respective app stores (Google has used its kill switch to obliterate malicious apps, while Apple is yet to exercise its app nuking powers).
Note: Apple regularly pulls apps from its App Store, but those who have purchased those apps are free to continue to use them.
The only bit that worries me is the refund policy. I don't understand why Microsoft says that it only 'may' refund the amount paid for the license for any removed product. I'd like to see this refund policy written in much plainer language.