In this passage, Hawthorne makes clear that whatever Major Molineux's political sins may have been, those who take such delight in "trampling on an old man's heart" are themselves far greater sinners in that their behavior makes them "like fiends."
When there was a momentary calm in that tempestuous sea of sound, the leader gave the sign, the procession resumed its march. On they went, like fiends that throng in mockery around some dead potentate, mighty no more, but majestic still in his agony. On they went, in counterfeited pomp, in senseless uproar, in frenzied merriment, trampling all on an old man's heart. On swept the tumult, and left a silent street behind.