That scene was so intense because at first, no one knew where the bomb would detonate, and Pearl and his pokemon were caught in the freaking lake. It's honestly lucky for Pearl that Saturn grabs him out of the water even though his intentions were to be aggressive and intimidating because the bomb does indeed go off in Lake Valor.
Pearl and Rickshaw arrive at Lake Valor, and while Pearl is swimming to the island in the middle of the lake to check it out, he's stopped by Saturn in his bubble machine.
