The most powerful attacks also require some form of possibly-silent chanting for focus. We've seen Saki do it a number of times to protect herself. Satoru has done them as well. It only takes a brief moment, but it makes a telekinetic blast devastating instead of simply strong.

I would say it was very likely Inui used chanting to defeat the ragworm on the surface, but didn't have the time underwater, partly because he also had to warn Saki. He killed it, but could not stop its momentum.