My guess is it would pierce his aura of invincibility if he went after a fast time and blew up or lost the race. People used to be so deferential to Mo, he pretty much did whatever he wanted over the final 800m of the race. Gebremeskel and crew ran 12:46 in Paris 2012 with a 54 second last lap, and then spent the next 5 years jogging while a 3:28 guy sat on their shoulders til 600 to go. They were terrified of him and were running for 2nd.
Thats why I have tremendous respect for Jakob. No fear of anyone, he goes to the front of every DL and says come and catch me.