Not sure if it's really true as the Kenyan press (like LetsRun) sometimes makes mistakes. It would be surprising as Birir is 42 now and we haven't seen any results for him since 2006 when he ran 2:24:08 at the San Diego marathon (he has a 2:11 marathon pb).
The Standard wrote:
The 2012 Boston Marathon champion Wesley Korir and the 2011 Boston winner Geoffrey Mutai lead a pack of more than 200 athletes who have confirmed participation in the inaugural Chemususu Dam Half Marathon to be held in Eldama Ravine on Saturday.
The 1992 Barcelona Olympics 3000 metres champion Mathews Birir is also eyeing the jackpot prize of Sh100,000 alongside emerging talented young runners in a road race that has been divided into five categories.