I think it's a reasonable interpretation and I agree with GP. APIs used to be seen as fair use and a way to compete, in the similar way to how IBM-compatibles are seen. However, when it became clear to Oracle that there is money to be had, they changed the very definition of copyright to get their fill. What's to say they wont mutate some other aspect of IP law in the future just to make you liable like they did with google?

If you're big enough, they will come after you. I think it's perfectly rational - and i'd argue smart - to cut them off early before it's too late.