Denunciation is an easy call for him and Pelosi in this case. They’re worried about losing voters who dislike Trump personally but are sufficiently open to voting GOP that they’ll seize on evidence that Democrats are just as boorish to justify it. And they’re probably also worried — or should be — that left-wing rage over Trump’s immigration policy will produce a James Hodgkinson copycat. Political leaders like Schumer crave control; the chaos and fury forever swirling around POTUS threatens that. One nutty Resistance fan going off is all it would take to scramble the midterms.

This dynamic, of a congressional leader conciliating while the base rages at his timidity, should also be familiar even though Schumer belongs to another party. He’s playing superego here to the lefty id. More clever liberals, like Brian Beutler, counter that drumming Trumpers out of polite society will police morals more effectively than intoning about civility on the Senate floor will:

[A]ll of them seemed to fundamentally misunderstand the stakes of the act, as if it were a symbol of a deterioration in discourse between liberals and conservatives, rather than an act of moral suasion that, if widely adopted, would impel Republican leaders to change the detestable ways they treat immigrants, asylum seekers, and other vulnerable people…

As Harvard has hopefully learned, disarming is an error. Spicer and Lewandowski should have been denied those fellowships. They should also wonder, every time they walk into a new restaurant, whether they will be told to leave. It is good that Spicer has been unable to cash in on his shameful tenure as White House press secretary with a cushy corporate gig, and it is good that Lewandowski lost his speaker’s bureau contract. Not just because turnabout is sometimes satisfying, but because other Republicans are watching, and if they understand that advancing Trumpist values comes with a cost, it might arrest the right’s slide into illiberalism. That’s something even reluctant factions of the political establishment should awaken to and embrace because all of us are along for the ride together.

That’s a highly naive view of tribalism in the age of Trump and what the reaction on the right would be if shunning Trump aides (and supporters?) caught on. He’d be better off making the argument from the id: Trump’s a boor, he revels in being one, he’s been abundantly rewarded politically because of it, yet the left is being told that Maxine Waters crossed the line. Why shouldn’t she cross it? They want to cross the line too! It’s satisfying personally and conceivably even effective electorally, per POTUS’s own example. Why should he have all the fun symbolically kicking people in the nuts with impunity?

Here’s Schumer making the case for civility in the most left-friendly terms: What would Michelle Obama do?