The contrast between entering other civilised countries and entering the United States is one of the things I hate about travelling. Every other country I visit manages to control its borders and have a pleasant, polite entry process, but not my own! I've seen border agents scream and holler at people who clearly don't understand English: there's just no excuse for that. It's rude.
The United States and Europe are political units of approximately the same population and area; there's no reason why entry into the U.S. must be so much more miserable than entry in the E.U., any more than there's a reason why we Americans pay such relatively high taxes for such relatively little in services.
I don't know the particulars of this incident, so I won't comment on it. The man's not a citizen, so he certainly doesn't have a right to enter, but I do think that the border exception to the Fourth Amendment is terrible, and that requiring citizens to share the contents of their electronic devices without a warrant is an invasion of privacy.