Earlier quoted context omitted.
If I'm not mistaken Rovio are based in Finland, where software patents don't hold much water.
They're selling a product in the US market, so they're subject to US laws so long as they want to continue doing that.
Now. If and when their _product_ is sold in US and infringes some US patents then patent owner can block selling that product and this is the only thing they can do. No damages no nothing. In Rovio's case the only thing Llodsys can achieve is to prevent Apple for selling Angry Birds in US. Nothing more.