Words matter:
A coup or coup d'état is the removal of an existing government from power, usually through violent means. Typically, it is an illegal, unconstitutional seizure of power by a political faction, the military, or a dictator.
Now Trump is not conceding and he's making spurious legal challenges all over the place which are being rightly laughed out of court. None of that is unconstitutional or illegal. It should be allowed to run its course and he will be turfed out of the White House when the democratic proces has run it's course.
When you begin language that frames it as 'a coup' you play into the language of demagoguery. You fan the flames of division in an already divided country and create exactly the 'Us vs Them' conditions in which someone like Trump thrives.
There's a very good reason why the newspapers aren't using the word 'coup' and I'd advise everybody from the left to avoid using the word too. It wouldn't be wise to accuse almost 70,000,000 of your countrymen of supporting a coup.
As I said. Words matter. So tread carefully.