His experience doesn't seem all that bad. It looks like they were merely doing their jobs trying to ascertain that they aren't making a mistake letting him in. If the immigration officer isn't sure of something (either because of an unclear answer to a question or a nervous vibe), it's not abnormal for him/her to ask for a more thorough check of the person. I wouldn't expect them to clear everyone with a quick, cursory glance of a passport or a green card.

I sympathize with him, but it doesn't look like his rights were violated in anyway.

You're setting a very, very, low bar for "doing their jobs". The reason we employ human beings at border points is so that they will, theoretically, use good judgement to allow the free flow of legitimate goods and travelers (i.e. not create massive delays without a clear reason).