He wouldn't be as driven to protect a human. However, he would still prevent them from ripping the thief apart. His is the personal code type of LG. He will follow his convictions without pause, so stealing is still bad, but facilitating murder through inaction is much, much worse.
And yeah, basically look at him as a Sunbro. He does good for the sake of it and will defend his "host" without fear or hesitation. Now, all he needs to do is glow gold and we are all good