If Christina had pulled a "Radar" and re-released Keeps Gettin' Better on Bionic would it had worked as a bonus track?

Yes. That is when she started getting "experimental" and futuristic with her music. She even mentioned it on the Back to Basics tour that that is what she wanted to do on her next album. There is a video somewhere.

I mean, after all it was a preview of what was coming next according to Christina herself. Not only that, genie 2.0, Dynamite and You are what you are as well. Even Falling in love again which is the song Birds of prey could never be.

To think People have the nerve to say Christina was chasing trends when truth is, she was dumb for announcing her vision then taking so long to release the album. Same thing with Tilt Ya Head Back which was released years before ain't no other man. Trend setter and atrl has to deal.

I think she was a little dumb to do that yes.
People tend to attack her because they feel she's a sound-bandwagoner, when the truth is that she is a true trendsetter.