Why Murdoch? Well, some people assume it is because I watch... I think Dr. Who? But that was actually completely a happenstance thing, as I've never seen a single episode of Dr. Who.
The real reason is... dun dun dun... free association thinking. It's just what popped into my head one night a few years back, and I have no clue why. I guess I thought it sounded a little funny, but it was also recognizable and believable as a planet name, so it worked. And now it's become this legendary thing in AI War, where the hardest planet tends to be Murdoch because it is the first one added and so tends to be some central hub world of critical importance or something.