I don't understand how your suggested calculation is non-arbitrary; you still seem to be picking some criterion and then doing math.

I don't understand what, if anything, you would consider non-arbitrary.

the laws of physics [...] just apply the exact laws of motion to the exact particle locations at every time step.

And why does that conflict with what anyone says about the "arrow of time"?

with high-energy intermediate states, you can get weak particles in your electric interactions; and then you get time asymmetry.

So you actually are suggesting that weak-interaction parity violation is responsible for the asymmetry between frying and un-frying eggs. OK, then. Do you have any actual evidence that it's so? It seems awfully implausible on the face of it, to me, but since (1) neither of us is a quantum field theorist and (2) so far as I know no one knows how to do the QFT calculations on anything like the scale required to understand what's happening when you fry an egg, I'm not sure that either my intuition or yours is to be trusted. So, I dunno: has anyone done the back-of-envelope calculations to figure out whether this works in some sort of toy model? have any actual quantum field theory experts given opinions on how plausible this is?