X and Y aren’t comparable is a rather common expression meaning X is much greater than Y (or vice versa) along some dimension. I suppose the logic is that you

X and Y aren’t comparable is a rather common expression meaning X is much greater than Y (or vice versa) along some dimension. I suppose the logic is that you wouldn’t actually weigh them against one another because the result is so obvious - compare here perhaps implicitly meaning to weigh both carefully. One can quibble with the logic of the phrase, but GP used it correctly.