No, not legally, but they will sic their lawyers on you and bleed you dry anyway.

Being sued for something like this sounds like a perfectly good way to make some patent lawyer very famous and yourself very rich.

Maybe I'm just naive, though.

The problem is you will be up against a legal team funded by millions of dollars and they will get you stuck in red tape for years. I don't think a lawyer would take that on commission. And I don't know a lot about it, but I don't think counter-suits are very lucrative in patent law anyway.