This is a pretty awesome hack. I already use my iPhone as a “desktop” sometimes when traveling (you can use the Windows app to have full-screen Remote Desktop sessions on an external display and a pocket Bluetooth keyboard) and have been looking at Android’s upcoming “desktop mode” with some interest, but being able to run native iOS apps in windowed mode on an external display would be icing on the cake.
Of course Apple will never support this and will hunt down and remove any way to change the class number to enable it on an iPhone, because we just can’t have nice things—we can’t even think about them.