The guilty always fake innocence. Why would the alleged innocent (doofylucy) fake guilty? What does he gain from doing that?

As  Republican Trey Gowdy said "If you are innocent act like it". So if doofylucy and his gang are in fact innocent why do they act so guilty? Why the desperation to shut things down if they will be vindicated?. Does anyone understand the logic of that? If you do please explain it. :)