yeah it does not count when they are hacking off the limbs of random peasants and farmers with scimitars, they have to blow themselves up and be an official isis member for it to count
by the way the whole "modern explosives" argument is pretty absurd in and of itself since plain old blackpowder works quite well at blowing people up according to the throngs of people killed in that manner intentionally and accidentally, and arabs were among the first to widely deploy grenades, cannons and "hand cannons" in the ancient world due to the close proximity to china.
a large number of the bombings you hear about to this day the killer used blackpowder (or something similar like broken down fireworks) not a high energy "modern" explosive.