User blog comment:Mexican215/So who was satisfied with the last battle against the Reapers?/@comment-2250460-20130205222107/@comment-4950455-20130213100155

Harbinger might well be blind, in the sense that it can't see anything except with the sensors that the Reaper IFF and stealth systems presumably block. The "eyes" are probably purely aesthetic.

But yeah, it is kind of a questionable scene, and the justification doesn't fit well with the whole "dodge the Reapers" mini-game, among other things. (Although it does fit with the way the Reapers in the prologue just ignore the Normandy).