It wouldn't be through Poland. You couldn't launch a interceptor from the U.S. because of the distance. So Poland may not be the best location, but it is preferred to locating them in Western Europe. In any event this is a problem for the U.S., Europe, including Russia. All have ongoing problems with Islamic terror, and all are potential targets. In any event interceptors are not nuclear mussels in the first place, so all the talk about aiming this, that or the other is irrelevant to the article at hand.
Bulgaria, Romania, Georgia or Cyprus would be the best locations.