Because he has 9.8 100m speed. He has the speed reserve to run 400m how he wishes.

He’s one of the most exciting up and comers! 🇧🇼

I mean, it's good that he found out early in the carrier how he actually runs faster, if you compare the 43.40s and 43.39s, you will notice that a more balanced first 200m in his 43.40s would've been much faster than his 43.39s where he blasted the first 200m.

Kebinatshipi has surpassed Lee Evans (43.86) and is closing on Butch Reynolds (43.29)