You are presenting the philosophical position. My point is, if it can be explained empirically, then why not? After all, in our post-modern times, there's certainly more sense in basing one's world-view on something that is scientifically credible than in arcane stuff that is casually dismissed as "old man's tales".
All of matter, including dark matter, is bestowed with mass by the force field of the Higgs Boson thar permeates the Universe. Can this be associated with "karma"?
My approach suggests that the major events in a person's lifetime are all ingrained into the long-term memory, which is a physical memory store. Perhaps, this stimulates some dark matter particle complex formation on the "soul" side.
This one is actually pretty simple. There seem to be 'hard-wired' laws of morality not just in the human brain, but also in all other organisms, including bacteria. In fact these laws are dictated by chaos theory. So, this 'judgment' part is the simplest from this dark matter point of view.
Well, this "soul as cold dark matter" theory of mine is all about physics; so, whichever way you approach this issue, what you state here will always be the end-result!
The point I'm making is, there is a very real chance that this is scientically validatable. In such circumstances, it has profound implications not just for our lives, but also for our polity. Currently, "Karma" is just a belief, and dismissed as wishful thinking by jurisprudence. But, if it is empirically 'kosher' then jurisprudence must factor it in it's calculus.
That polity aspect apart, even at the individual level; a person would become more moral if s/he realises that "karma" is scientifically binding, and that the actions of the individual in this life affect their prospects in the future life/ lives to come.