You can test this easily by going and finding a random elite in the wild and having a friend or companion attack it for x amount of time, then taunting it and having them stop attacking. As long as they do not start generating threat again, the npc will continue to attack you.
Reread what you just quoted. I prefaced the phrase you bolded by explicitly stating that "if the target hasn't been attacked yet". This still remains completely true. Taunt only provides useful amounts of threat when appreciable amounts of threat have been generated on the target in the first place. That was the entire point of the referenced paragraph.