The metaphor attempts to lead the reader to the answer themselves. When the Great Philosopher asks which has more value, the reader should be able to answer that question even if the answer isn't written in the text. Of course, both $30 in bills and $30 in coins are worth exactly $30, despite the differences in their mass. Through the magic of reading comprehension, one can link that to the original question: despite their differences in mass, both are equally valuable, because both are breasts. The question was invalid.
The respondent being analysed has in fact recognised this subtext equally and the result of their lack of understanding has happened in lieu of this.
Ironically, I'm having trouble parsing this. Can you rephrase it?