Last month, in a game against the Tampa Bay Buccaneers, the San Francisco 49ers’ star defensive end, Nick Bosa, celebrated a routine sack with a cheerful and ungainly series of hip-swivels and fist-pumps, not unlike the movements of an automaton gaining sentience.

This time, though, the scolding, humorless masses don’t seem to mind. So accustomed are we to a politics of mischief and defiance that there has been little of the liberal pearl-clutching that serves as lifeblood for the right-wing commentariat. It feels especially pointless to note how many of the talking heads who are now gloating once groaned over athletes daring to oppose the former president. Not even the N.F.L., which takes a perverse pleasure in doling out fines for celebrations it deems political, violent or sexually suggestive, could be bothered to feed the outrage machine. The league, its spokesman stated last month, takes “no issue” with the dance. If anything, the move’s popularity marks a new frontier: Trump as the mainstream, no longer an outsider but a figure so banal and impervious to scandal that people can muster no more than a sigh — or, perhaps, a little wiggle — when they encounter him, suddenly, on the field.