Why is it biased? Why because it mostly applies to Islamic terrorists. It's bad, just like 'illegal immigrant' is bad because, oops, judgmental…

Via Slate: 

…The big problem with illegal immigrant wasn’t that reporters applied it inconsistently—the term simply became too judgmental, too toxic for neutral copy. So, in 2013, the Associated Press Stylebook dropped it.

Likewise, I think we’ve reached the same point with the T-word. Reuters—a less influential force in American journalism style than the AP—agrees with me. From its style guide:

Reuters may refer without attribution to terrorism and counterterrorism in general, but do not refer to specific events as terrorism. Nor does Reuters use the word terrorist without attribution to qualify specific individuals, groups or events.
I think that’s the right policy, and the AP should follow suit.

Eschewing both terrorists and illegal immigrants alike is in keeping with a broader and widely accepted best practice for journalists: Avoid labels! When possible, describe what people do instead of labeling what you think they are.