I don't think it's fair to criticize metaphor as bullshit insofar as the definition of bullshit is something like "saying things without regard for their truth

I don't think it's fair to criticize metaphor as bullshit insofar as the definition of bullshit is something like "saying things without regard for their truth values" (paraphrasing Harry Frankfurt) because metaphor doesn't have the sort of truth requirement you seem to think it does.