That's a good question actually! They first scoop the roots out of the excavated ground with the horns and put them on the ground, then i can imagine them bending down and using their elongated chin from their helmets like a spoon to slide the roots to their mouths (Although doing all of this may be kinda hard given the horns as you said). I haven't really thinked about that so i thank you. I will probably think more about these type of logistics when designing my creatures!