Everything Macron does here is calculated. It's the difference between leaving no tip and leaving a nickel as a tip—the latter is a no-ambiguity message, "This wasn't oversight, it was a deliberate choice"
And it's not just that Macron doesn't shake Trump's hand, it's that his hand moves to Zelenskyy's back after letting Trump hang in midair
The contrast between his admiration for one man and contempt for the other couldn't be clearer