Still. maybe building something, leaving your mark or the mark of your people on the world, is quite a strong trait in human existence. We are still scratching our heads when it comes to the pyramids in Eygpt, Stone henge in the UK. hard for thousands of people with low tech society, but not when you are a giant. "We are the most Dominant. Look what we can build!" can get people on your side more than the threat of destruction
The most obvious advantage is he's always got the high ground. You can't build castle walls tall enough to keep him out, so the entire concept of siege goes away. He can also perform the job of artillery. Most of human warfare is just throwing heavy crap at each other. He could pick up a bunch of cars and toss them like pebbles, which should be more than enough kinetic energy to bust most walls, even castles/bunkers.
