Don't go by the submitted title only. He was detained for hours with no food or water, beaten up, strip-searched, forced to give blood samples.

And yet in practice, this example is rare. "Can" is not "should" or "is immune from criticism for doing so".

You completely missed the point. The issue isn't denying entry, it's denying entry for this reason.

He was detained before the image was found. It's most likely there is another detail to this story that is being left out.