Jehu, as even that WT article explains, was a hypocritical religious zealot who took it upon himself to kill those who worshipped Baal and then turned out to be no better than any of his victims. According to 2 Kings 10:29, he took up golden calf worship.
Still, in the eyes of the WTS, anyone who was prepared to swing his sword and slaughter those who followed a different course of worship is a decent bloke. Especially when he did it in God's name. (Did he yell out Allah Akbah! as he beheaded them?) In fact, as the opening paragraph of the WT article claims,
"Jehu was a champion of pure worship. In carrying out this role he was energetic, prompt, relentless, zealous and courageous. Jehu manifested qualities that we would do well to imitate."
Really, he sounds a bit like the leaders of the Crusades of the Middle Ages who were dispatched by the Pope to slaughter the enemies of God. Does the Watchtower think they were "champions of pure worship", manifesting "qualities that we would do well to imitate"? What about Ron and Dan Lafferty, the fundamentalist Mormons who Jon Krakauer wrote about in "Under the Banner of Heaven"? They did a pretty good job too, slaughtering Brenda Lafferty and her 15-month-old baby because she wasn't playing the polygamy game as they believed God required. They were relentless, energetic and zealous as well, but shucks, it turned out they were wrong too, just like Jehu. Ah well.
Personally I think it's a bit worrying that the Watchtower puts a deeply flawed, bloodthirsty, hypocritical and self-righteous biblical figure like Jehu up on a pedestal and says to Witnesses, "We wish you could be like him." For a religion that claims to be the epitome of kindness and Christian love, it's a pretty dodgy position to take, holding up as a role model someone who relished the idea of killing anyone who followed a different religion and then mixing it up with the usual polemic about the dreadful APOSTATES and the necessity to "avoid the company of DISFELLOWSHIPPED individuals."
Charles Manson heard messages in the "Helter Skelter" song that led him to slaughter Sharon Tate. You kind of hope there are no mentally imbalanced individuals lurking in congregations somewhere who take the Watchtower's commendation of Jehu a little too literally.