I've always thought modron = bureaucrat.
I do think it's possible for absolute law, though. It is conceivable to me that the laws are a priori, that they existed before the plane of lawfulness and before the whole multiverse (I'm not saying they did, I'm just saying its conceivable.
I also think it's possible for complete chaos, just highly difficult and very improbable. Something to consider, is that we are using these terms to mean both the nature of the land/culture and the action of the individual. Having one lawful being on the plane of chaos doesn't change the nature of the plane, it becomes the exception which proves the rule.
The other thing is that when we are dealing with deities, is is hard for us mere mortal sages to understand the full scope of their actions.
The rules of the game (or lack thereof) may be too complex to understand.