Game Guardian does not appear to work on devices that have x86 processors(Tab 3 5210 and such). It has nothing to do with your rooting method or SU app. I know because I have multiple devices including a P5210, and the P5210 is the only device I cannot get Game Guardian to work on. All my research has led me to believe it has to do with the x86 processor... Sorry, but at this time your SOL