Q: Why not support Android 2.x?
A: Sorry, Android 2.x lacks a core mechanism that Greenify mainly depends on. It's impossible to achieve equivalent functionality in Android 2.x. If possible, please consider upgrading your device to Android 4.x (CyanogenMod is a good choice if no official 4.x upgrade). If you are out of luck in upgrading, you can also try one of the alternative tools I mentioned in the app description of Greenify on Play store, such as "App Quarantine" (for most users) and "Autostarts" (for super users).
