Well, my speculation...
I think it is purely human revenge driving him vs any implant effects. The implant just gives him the strength to apply his revenge with extreme prejudice
I think the implant will ultimately take his humanity and he may be feeling the early effects of this but it remains a human reaction at this point.
Yeah, Walter has pretty much told us where he is heading and while it won't be pretty, it might be helpful to get rid of the observers.
Ultimately it is likely that all this bad stuff will be reversible. It seems that everything is reversible in this series. :)