I don't know why a horrible mass shooting should be used to make a point about racism? 
Yes some people are racist, yes racism is bad. Yes it is possible to use anti-terrorist policy in a racist way.
But, terrorism  has a legal definition and clearly violence must have an ideological basis for it to be considered terrorism. The reasoning in this article is deeply flawed and does a disservice to those advocating for a balanced but effective response to actual terrorism.
Unless there is some evidence still to come, this was a truly horrible mass shooting by a homicidal maniac but to describe him as a terrorist is both inaccurate and needlessly political.