Should Trump hirelings be confronted in restaurants? Delightful as it was when the president’s press secretary, Sarah Huckabee Sanders, became the latest of his favourites to be thus embarrassed, the resulting civility debate has seemed fairly, viewed from the UK, theoretical.

Few British restaurant owners will ever have to have to choose, as did Virginia restaurateur Stephanie Wilkinson, between adherence to long-cherished codes of civility and the clear risks of denying service to someone who has chosen, like Sanders, to promote the interests of a child-caging, homophobic, woman-molesting, massacre-finessing, Putin-appeasing barbarian. (Huckabee Sanders was evicted before Trump also barged in front of a 92-year-old woman he had kept standing in the heat.)

Equally, even with our own prominent Trump loyalists – Farage, Johnson, Gove, Murdoch, Morgan, Banks – what are the chances, for a UK citizen, of finding one at the next table? But that their particular perversion appears, mercifully, relatively rare does not, as Becca Harrison has just demonstrated, mean we should not make contingency plans.

Shortly after Piers Morgan’s latest prostration before Donald Trump – the one involving free chocolate – Harrison found herself, she writes in the New Statesman, sitting in the same Kensington cafe as the interviewer. She used Twitter to ask if she should – and then confirm that she did – go over and call him “a fascist-enabling cunt who was doing serious damage to our country”.

Morgan, adhering to the Trump template for women-humbling, tweeted back, in effect, that Harrison was insufficiently physically pleasing for him to take her seriously. Beyond, that is, alerting his zillions of followers to this outrage. She should, he tweeted, update her profile picture – “been a few years hasn’t it”.

Before Kensington cafes are inundated by women hoping, with the help of this authority, to gauge their own claim to self-expression, it’s probably worth adding that Morgan, following Harrison’s NS piece, said it made him glad he was (temporarily) leaving the country: “People are losing their minds.”

Usefully, as he confirms the huge potential of homegrown, restaurant-based resistance, Morgan also offers some hints to future protesters. Even if the c-word can seem to many of us – all right, to me – in one of the Referendum’s many unintended consequences, the only word that, in private, adequately represents the architects of Brexit, that word also permitted Morgan to portray himself as a bit of a victim, even to people who abhor him.

No ingratitude, or disrespect to Harrison, a protest pioneer who chose an obviously accurate term under pressure of time, but that epithet, as opposed to “fascist”, now assists Morgan, the UK’s premier pussy-grabbing apologist, lead bitcher at “snowflakes”, “grotesque” Madonna and “feminist fraud” Emma Watson, to diddumise himself as the victim of a foul-mouthed madwoman. (Harrison is a university lecturer and writer.)

Compare that with the difficulties of Huckabee Sanders and her civility-minded sympathisers, in explaining why restaurant protesters who have seized these chances directly to address high-status brutes should have allowed eating-out norms to mute righteous engagement. Stephanie Wilkinson remained, when reclaiming her restaurant table, infinitely more civil than Huckabee Sanders, with her well-known fondness for insulting journalists. Similarly, the US teacher Kristin Mink demonstrated, when she approached Scott Pruitt – Trump’s lead environmental trasher, investigated for the misuse of government funds – that it is possible to retain the moral high ground even as you ruin someone’s meal. Civilly, child on hip, she asked Pruitt to resign, “before your scandals push you out”. He quit days later.

Margaret Hodge: happy to loose a broadside at Jeremy Corbyn. Photograph: Murdo Macleod/The Guardian

Given the precise targeting of these encounters, and the offences against whole sections of humanity for which, on the other hand, their targets are standard-bearers, US defenders of civil norms have been hard put, in various stately editorials, to explain how the rebukers can be faulted – except by political adversaries who already loathe them. Why, as loyal child cagers, should Kirstjen Nielsen, and her colleague, Stephen Miller, expect quiet menu-time in (separate) Mexican restaurants?

Maybe it’s even a duty, on the part of their fellow diners, to address Trump’s inhumanity? What, if he was out to eat, would Jesus do? In Nielsen’s case, activists shouted “shame”; Miller was told: “Whoever thought we’d be in a restaurant with a real-life fascist begging money for new cages?”

Supposing there is, as Sanders’ champions suggest, a code of conduct that finds the civilian tactics, rather than Donald Trump’s, to be the unacceptably rude ones, these encounters make the case, more powerfully than any scholarly distinction between politeness and civility, for its revision, in both countries. Since the rule that allows the side aligned with pussy-grabbing and “crooked Hillary” to lecture a restaurateur on civility is the same one fostering the idea that, because he speaks so politely when he wills on economic ruin, and is never coarse when he deplores all abortion, Jacob Rees-Mogg is a civilised person.

Meanwhile, in the Labour party, sticklers for correct form – and since we’re here, what is Momentum’s current line on pardon? – recoil, for appearance’s sake, from Margaret Hodge’s verbal attack on Corbyn, a man renowned almost as much for his politeness as for his tolerance of antisemitism. What will people think? That, prior to Becca Harrison, US-style restaurant protests had yet – fortunately for Cameron, Johnson, Farage and hungry fellow vandals – to catch on in the UK, such public restraint, under such provocation, surely indicates a concern for politeness so excessive as to be practically pathological.

In some circumstances, as Margaret Hodge, the US protesters – and before them, Mary Wollstonecraft – have argued, civilised norms need challenging. And if one outcome is that David Cameron never has another date night, there are worse forms of ostracism.

• Catherine Bennett is an Observer columnist