That's a beautiful way of putting it. Making responsibility a function of proximity and ability puts the burden on what we would otherwise intuitively think carries it: Middle Eastern countries and the West. To be fair, I think the question being asked is more of: "Will our open borders (I know, not completelyopen, but still) allow the IS to infiltrate the West?" That's more of an understandable question but I would still think the answer is the same regardless: we should still help these people out. The fact that terrorism happens regardless of your status as a refugee or domestic citizen further proves the point that this fear is unfounded. Hell, even if it is somewhat founded, relative to the amount of lives that could be saved, it's miniscule. Logically, I think the expectation for action increases with proximity and increases with ability
The question becomes "does being Muslim or Syrian predispose someone to be more likely to commit violence?"