eal401,
You don't appear to be following the thread. The quotes you selected are replies to other questions not initial statements. As a result you are simply argueing for the sake of argueing. However dealing with the two questions:
The question you posed "If the crew are dead the passenger sat at an exit does what exactly ?" Assuming they have survived they get out, assuming they can move etc. etc. Does this answer surprise you ?
The second question you posed, "why are seats situated at an exit". Ideally they are not, in that most exits have to be clear. In the case of certain types of exits, they have a naturally lower flow rate ( by virtue of their design) and seats may well be placed adjacent to them since the design flow rate is not impeded ( from a regulatory standpoint ) by that fact. In the case of main exits they will be clear but of course there will be seats at some point fore and aft of them that will qualify as exit seats for the purpose of the discussion. It does not follow that these seats have to be occupied although they are likely to be. Seats have to be somewhere, it is how the business operates.