I would suggest that any BOB list that is centered around so called "space blankets" for warmth is likely to be woefully inadequate in other areas as well.

To me they are little more than thin and quite fragile one time use tarps. They are not blankets. They have zero insulation capability, and the supposed heat reflection properties are not much use in the vast majority of situations. They will help keep the wind and rain off of you, and that is about all they are really good for, IF you can keep them in one piece while trying to use them.

They have two things going for them in a BOB though. One is they are cheap, and the other is they are lightweight and don't take up much room.

My personal opinion is that most people would be better off with an emergency poncho or a 55 gallon garbage bag as they will keep the weather off of you as well as the space blanket will, while being somewhat less fragile. Cost, size, and weight is not far off from the space blanket.