I agree...his actions meet the legal definition of domestic terrorism...use of force and violence to further a political objective. He's achieving it, too..LAPD will now re-examine his allegations. How about that?
Another domestic terrorist, Tim McVeigh, was successful, too, in the use of mass murder to advance a political objective...let's remember that it was after Oklahoma City that congress held hearings on Waco and Ruby Ridge, the incidents that supposedly motivated McVeigh to bomb the Federal building.
Sadly, violence can be a very effective way to stimulate government action.
In his manifesto, Dorner says he will "make policy" for LAPD...and will only stop killing when his demands are met.
So we can call them domestic terrorists. But, in my opinion, dig into their psyche deep enough and you will find the driving force behind the violence is not the stated "Cause" but a desire to kill due to serious and longstanding mental health issues. Offenders like McVeigh and Dorner wrap their real need---to kill people--in a package they can explain and justify...hence, the political rationalization...and it also helps them pick their targets.
Don't get me wrong...they are legally sane...meaning, they know right from wrong, they know the nature of what they're doing, but they are deeply disturbed, violent and therefore dangerous.
So, if he's caught, by all means, prosecute him under the terrorism statutes as well as for murder...but we would do well to understand that the true motivation is deeper and darker than the stated motivation.
Our problem is that we need to understand, to have it all makes sense, when it's not understandable and it is senseless. So, simple, clear explanations like revenge and terrorism allow us to explain away the inexplicable...to answer the question, "Why would someone do THAT?"
It's like explaining a kleptomaniac's stealing by saying he wanted something and just didn't want to pay for it. Or to explain rape by saying the perpetrator wanted sex. Or to explain a peeping tom by saying he wanted to see a naked woman. In each case, there is an element of truth to those explanations, but those explanations do not fully explain the behavior.
Dorner kills to satisfy a peculiar need that only he, or someone like him, can fathom.
Anyway, that's the best I can figure it.
"The great enemy of the truth is very often not the lie, deliberate, contrived and dishonest, but the myth, persistent, persuasive and unrealistic." President John F. Kennedy