My first reaction to your objection was that the informal theory "heavier objects fall faster" inherently has one parameter per object (and that Galileo's objec

My first reaction to your objection was that the informal theory "heavier objects fall faster" inherently has one parameter per object (and that Galileo's objection more or less goes through against it) whereas you are discussing a two parameter theory. But on reflection I think you are right: "heaviness" could simply describe a derived quantity weight/mass.