Hi Hemnath!
Actually, that article does not address when a guest OS does not support Retina displays, and you're running its VM on a Retina display.
I am running OS X Lion under Parallels Desktop 13, and the "Retina support" that it features actually blurs the display output of OS X Lion when it is shown on a Retina display and the virtual display adaptor is set to "Scaled" (because Lion on Parallels does not support anything else). If anti-aliasing was able to be disabled for a Scaled display, it would make the virtual display appear sharper on Retina displays.