The sober version of that was that, in theory, having so many Muslims and other cultures in our cities was our best protection against WMDs being used against us.
Indeed, if the knee jerk reaction to such attacks was to intern or expel any people merely for similar appearance (or cultural signifiers), we'd only be helping them muster a sizeable army at the border between us and them.
Frontal warfare is a thing of the past; we are thouroughly interspersed. Except for a certain part of the world which has been all-but purged of westerners.
Anyway, regarding my opening paragraph: I. Was. Wrong.