He used a picture out of context to make his incorrect point.The debate isn't whether he was wrong as the figure of 600,000 last year testifies, what has become clear Brexit has failed to get any control over our borders, so the question is why.
No doubt you'd claim a lady using someone else's photo on a dating site, would hold "more commitment and principles" than others.
It's not principled to misuse a photo in order to carry an argument. It's disingenuous.