And a law itself is no excuse for killing other beings... I'm afraid erradicating the Vajra may very well become the law in Frontier now...
AFAIK there aren't any Zentradi in Galaxy... what would put blame in the humans of Galaxy... who may be no humans anymore, but more heartless and mercilessly logical A.I./Cyborgs now... (take Grace's actions as an example).
Now, just like Luke Skywalker said once, hehe... "There are times when the end justifies the means. But when you build an argument based on a whole series of such times, you may find that you've constructed an entire philosophy of evil." Grace faction is pure self-righteous mechanical evil...
More and more I find similarities between Frontier and the Dune novels too...