I'm not the OP, but a company I worked for once had reason to set up a US presence, but decided against it because once you have a US entity, patent trolls have someone to sue in their jurisdiction.
Exactly. This is also one of the big reasons why Stripe Atlas is not necessarily a good idea for companies from outside the US.
It's not being in Poland that helps, it's being outside the US that matters. USA is the only country I know where you can successfully run small companies into the ground just by suing them (for pretty much anything, but patents are a good vehicle for this). The legal system is such that small companies are at a distinct disadvantage (because of complex precedent-based law and legal fees).