I still think it's pathetic but lets underline what broke Maggie.
If the gunmen didn't want the camera, the kid would have lived.
If they had left the kid under the bed, the kid would have lived.
If she wasn't using the kid as a human shield she would have died.
She's ecstaticly happy and over joyed that he died to save her but she feels rotten about surviving under those terms and feeling good about it.
If the kid just would have got in the Van when he was supposed to, every one would have lived.
And Gary... You don't lift the bed off it's bolts with a lever, you use the lever to hit the kid until he gets out to stop you hitting him. In the real world it would not have been that easy to move the bed, or it would have already been stolen/used for firewood in winter.