User blog:Garhdo/Plot hole?

it just occurred to me that there is potentially a large plot hole in Mass Effect 2. I was wondering if anyone knows an official explanation because it is starting to bug me.

After the Collector Cruiser attacks the Normandy the crew is at their mercy. There are several escape pods floating defenseless in space, Shepard is dead and falling to the planet's surface, and yet at this point for some reason the Collectors leave, despite the fact that they are already beginning to harvest humans, and will later try to obtain Shepard's body.

My point is why did the Collectors not obtain Shepard's body, or abduct the escape pods, then and there. I haven't read the comics so I am unaware if it is explained there or not. Can anyone help?