You're being facetious of course, but:

We can in principle associate some minimum weight to abstract units that are the result of computation, right?

We know the (currently assumed to be optimal) procedure required to generate / store / transfer them, right? We also know the physical limits of efficiency of implementing some basic elements assumed to be necessary for any program, independent of model of computation (well, I don't really know them, but I remember reading an article on this a while ago).

So in principle, we could associate a "weight" per unit of Bitcoin, something along the lines of "minimum physical structure necessary to generate / store / transfer one unit".