It means a slight angle. Flat down on a table top may be uncomfortable for viewing in portrait mode. The Surface, with the kickstand out, would sit at an uncomfortable 90 degrees in portrait mode. With the removable magnetic catch iPad 2 cover, you simply detach it from the iPad, rotate the iPad to portrait position and set it on the detached triangular iPad cover. It sits at perhaps 15 to 20 degrees angle off a table top. Makes for easy operating. I have both docking, and bluetooth keyboards, rarely use them as I find the touchscreen keyboard sufficient for 95 percent of activity. So okay, the Microsoft keyboard has a connection port. Bluetooth suffices for me most of the time, and is convenient for wireless keyboarding.
Where are you getting the 90 angle stuff from? MS stand kicks it at a 22 degree offset. Which is why they made the camera able to adjust to that 22 degree offset.
Not a single picture of the device in kickstand mode shows it at 90 degrees. That’s simply FUD.