I completely disagree with Mr. Saunders.
Motive is of the utmost importance and to find the motive for a horrible act, like a mass murder, is a must for it will and should determine how law enforcement and intelligence agencies deal with it.  A lone wolf act is one in a thousand, violent acts carried out by individuals motivated by radical religious and/or political beliefs  are carried out in a systemic fashion and deserve an entirely different response.
What Saunders is implying is that as western  societies we have no right to make a 'value' judgement as to who is carrying out the terror against us.  We do.  We can easier accept that mental health issues can bring a person to psychosis where
he carries out a violent act, but it is more difficult for most of us to accept the pre-meditated violence carried out by for example ISIS.  As a society we hav a duty and a right to differentiate between different kinds of violence.  It is our
duty to understand the underpinnings of it.