Well Tom Clancy almost defines the "Techno Thriller" genre and the writing is not too complex so try some early Tom Clancy on him.
Go to the bookstore and buy the hard-back copy of "Cryoburn" by Lois McMaster Bujold. It contains a CD of most of her other books. Give him the Miles Vorkosigin books.
Try Isaac Asimov "I Robot" - robots are created with the 3 laws of robotics - and the stories show how despite these hard rules, robots can cause problems.
Vince Flynn has a bunch of military thriller books he may like about a guy (Mitch Rapp) who becomes a leading terrorist-hunter. Not exactly PC but not too bloody. For example: A small terror group trains some people to smuggle a bomb into Washington DC "Memorial Day". The book bounces between the terrorists and the hunt for them.