If someone doesn't speak any Polish or maybe only limited Polish does that mean he/she loses the right to "be" Polish??
Language is such an important factor, determining national identity (especially in our part of Europe,
where many people had to struggle to keep their language, culture and heritage very often risking
their lives for it), that yes - I would say that if someone doesn't speak Polish and doesn't make
a real effort ('real' is the key word here) to learn it, then his Polishness is lacking something vital.