Multiple things can be true at the same time, despite the binary thoughts most people have.
DJK could be a cocky ass.
DJK could have had drug problems.
DJK could even have been a PITA.
But even if that is all true (don't know), the following could also all be true...
KF could have known about all these things.
KF could have covered for Doyle.
KF could even be a racist piece of ****.
It's not always a simple choice between is somebody a stand-up person while being treated horribly, or a horrible person getting what they deserve. There can be horrible people that still get **** on by racists.