I'll make a few comments on this:
I agree with most of what Piper says. In addition, just because Trump won doesn't mean Christians should instantly fall in line. We need to maintain our standards. We need to maintain our distance.
That said, there are some odd things about Piper's lengthy statement. I agree with him that Hillary's position on abortion is morally disqualifying. That, however, is an understatement. There's a long list of things that make Hillary morally unfit to be president.
Conspicuous by its absence was any reference to the outgoing president and his lawless administration. Surely Obama was morally unfit to be president. So was Bill Clinton. So was LBJ. So was JFK. So was Nixon.
Moreover, whatever we might say about his personal morality, Jimmy Carter lacked the wisdom to lead the nation or the free world.
Which makes me ask: does Piper have a policy of speaking out on the moral fitness of a US President, or is he making an exception in Trump's case?
On a related note, isn't this a day late and a dollar short? Why not express his public disapproval during the primary season? Why wait until the game is over? It's way too late to change the numbers on the scoreboard.
Finally, public figures rarely make good role models. It's misplaced idealism to have any expectation to the contrary.