I really hope that BlackBerry becomes the 3rd platform for mobile devices, and not Windows, because that will increase the chance that both Windows (on the PC) and BlackBerry (on mobile devices) will use open standards accessible to all.
I failed understand your train of thought here. Assuming Windows Phone takes 3rd place, how does that hurt open standards?
Are you talking about IE? IE10 on WP8 seems to be plenty fast if not faster than Safari or Webkit and seems to have decent HTML5 support. On the other hand, if BB10 takes 3rd place, all top three mobile platforms will use Webkit and then web devs will ignore the standards and code to the quirks of Webkit and stop testing on other platforms like Opera,Firefox or IE.(already happening since a few years in the wild). This will hurt open standards on the web and will favor one particular implementation.
Perhaps you're referring to Office on mobile when you say open standards?
I think the poster just has the general idea that having the same platform (Windows in this case) on both PCs and phones will make the platform vendor more likely to rely on proprietary integration between them, rather than be forced to use open standards for communication.