Hard to tell from the pic, but if it uses the basic hardware, I would be very concerned. These speakers are pretty heavy, and the weight extends far from the wall. If you use a shelf like that, go to a hardware stood and get two of the 6x6 aluminum corner brackets. Mount those to a stud in the wall with a big screw, put the shelf on top, and you should be okay.

Panny 3000 PJ, 118" Carada, Denon 3300, PS3, Axiom QS8, PSB 5T, B&W sub, levitating speaker wire