Boston Marathon: What to Do About the Non-Finishers' Times?

The initial Boston Marathon bomb blast came at precisely 4:09:43 from the start of the race; the second explosion just 12 seconds later. In the wake of such monstrous acts, an estimated 4500-5000 runners were never able to complete the course, denying many of what would have been a singular, remarkable accomplishment.

It would seem to me that a fair gesture would be to credit each of those competitors with the precise finishing time of 4:09:43.  While 4:09 is certainly a respectable time to run a marathon, it's not a world-beater by any means, so why not simply grant it to all those who were unable to complete the course through no fault of their own?