Nobody has said it's excusable. John B's post was simply pointing out that her outspoken views on certain subjects just increase the likelihood that her murder was politically motivated. He wasn't saying it was justified.
Personally, I found her pretty objectionable and disagreed with her about most things. Her "Let my people go" speech in the EU parliament was one of the most desperately pathetic things I think I've ever seen from a British politician. But I'm still absolutely appalled by her murder and would never wish that on anyone.