I wouldn't rule it out based on the picture you showed. Lay on the ground and study the major branches. How big would the canopy have to be to be a good tree? Just because it's not the typical (whatever that is) Juniper form doesn't mean it wouldn't be a good or even great bonsai. Look closer. Look at the nebari while you're down there. (Take a toothbrush and wire brush, to it)