Sure they can. That's what an End-User License Agreement is: you own the software but you must use it their way. In addition, since it's a Beta and isn't a 'public distribution' yet, they can pretty much do whatever they want.
They have a similar clause in the EULA for gmail. Which is why no one should ever use gmail for business purposes (or anything else that's confidential). Google can read your email at any time for any reason... Which is why we'll probably never see a non-beta version of gmail...
That and they can't be sued if it borks your system.
