Don't know why the link to the game was changed to Halo 5 Forge's own page. From what I'm reading, all the links posted by major news outlets point to the bundle, the official link points to the bundle, and people can't even download the game unless they download it as part of the bundle. As such, pointing people to the direct, non-bundle page is just setting people up for confusion.
Also, as far as I know, it's impossible to launch the game on PC without going through the PC version of the official Halo app first. If someone is just able to launch the game without the Halo app running in the background, then I don't know how to achieve that since Forge on PC is a Windows Store app, not a Win32 app, so launching it directly is forbidden.