The Three Laws of Clusters
Well, more like Two Laws, but the wording in the clause these lads have added to their software licence to effectively prevent military use of their work sounds very similar to Isaac Asimov’s Three Laws of Robotics.
It’s a pity this exception and others like it can’t be built into the GPL and similar licences, but they really can’t: the GPL’s beauty is it’s simplicity, if you take that away you defeat the entire purpose.