The logic of a ban on Muslim immigration and travel was spelled out in a syllogism of blood yet again on June 3, as England was hit with its second major terrorist attack in two weeks.
Liberal Democrat leader Tim Farron, meanwhile, backed Khan's call for Trump's invitation to be rescinded, claiming the United States president "insults" national values at a time when the country is still grieving over Saturday night's ordeal.
Khan received support across the pond too, with his NY counterpart Mayor Bill de Blasio saying: "Mayor Sadiq Khan is doing an extraordinary job ..." He calmly explained his opposition to Trump's proposed travel ban on visitors from several Muslim countries.
Khan tells BBC that he has no interest in Trump's offer: "I don't want to be the exception to be allowed to go to America".
A day after bombings in NY and New Jersey, Khan tells The London Standard that attacks are "part and parcel" of life in major cities.
Trump appeared to misconstrue the statement on Sunday when he tweeted: "At least 7 dead and 48 wounded in terror attack and Mayor of London says there is "no reason to be alarmed!"
But Trump then took his criticism a step further as he said Khan's excuse was "pathetic".
"It is a reality I'm afraid that London, New York, other major cities around the world have got to be prepared for these sorts of things", he said.
May declined to directly criticize Trump for his tweet, which has prompted a fierce backlash in Britain.
The next day, Khan tells Amanpour that he isn't going to reply to the President's son.
Attacks at the London Bridge and Borough Market kill seven and injure nearly 50. In the immediate aftermath of the attack, Khan said there was "no cause for alarm" when referring to a visible increase in police activity on the streets of London.
"The invitation has been issued and accepted and I see no reason to change that", he said.
"I don't think we should roll out the red carpet to the president of the U.S. in the circumstances where his policies go against everything we stand for", said Sunni Muslim Mayor Sadiq Khan, in a statement that left some ambiguity about whom he meant by "we".
They said of Mr Khan: "He has risen above this crisis of death and destruction, as mayors continue to do, to alleviate fear, to bring comfort to his people of London and to give support to the first responders who continue to protect, defend and provide emergency care to his people of London. MSM is working hard to sell it!" Cancel the state visit and tell Trump where to get off. "I think that's an important message".
Mr Khan's spokesperson had described the first round of presidential tweets as "ill-informed" - and said they had deliberately taken his remarks out of context.
"When you have a special relationship it is no different from when you have got a close mate".
After several repeated questions from journalists, Prime Minister Theresa May suggested at a campaign event that Trump had been wrong to criticise the mayor. The last time I checked, Great Britain did not (yet) officially "stand for" the Islamic radicalization of its youth, the precipitous adjustment of its demography in favor of Islam as the majority religious practice, or the passive acceptance of semi-regular religious-motivated mass killings in the names of "diversity" and "tolerance".