It's some sort of PR thing where people in a road race will start before Kipchoge and those who beat him get a free entry in the mass marathon that will be held on the Olympic course the same day as the Olympic marathon.
If he took it seriously, how fast could he run at 36?
Kipchoge hasn't run a 5000 since running the Paris DL in 2012 (July 6) after missing out on the Kenyan Olympic team (he ran 12:55) . Hell, he has only raced marathons for years. His last half marathon was Delhi in November of 2016.
https://www.insidethegames.biz/articles/1114170/paris-marathon-2024