Do you think the article is being fair in stating that
the "pacifist leanings" of the Watchtower and his JW parenting played a
significant role in his murder?
I think "pacifist leanings" is a fair and accurate way to describe it.
Although JW's do not embrace pacifism as a philosophy and are therefore not pacifists in the technical sense, there is a functional equivalency that makes it difficult to distinguish between the two.
This includes, (But is not limited to) not owning firearms for the purpose of self defense, not studying martial arts or allowing their children to, not serving in law enforcement, and not coming to the aid of a police officer even if you specifically directed to do so.