Parsimony is good except when it loses information, but if you're losing information you're not being parsimonious correctly.
So: Hamilton's rule is not being parsimonious "correctly"?
probably not. I'm not exactly sure what you mean by this question since I don't full understand hamilton's rule but in general evolutionary stuff only needs to be close enough to correct rather than actually correct.
In two posts, Bayesian stats guru Andrew Gelman argues against parsimony, though it seems to be favored 'round these parts, in particular Solomonoff Induction and BIC as imperfect formalizations of Occam's Razor.
Gelman says: