It is simple: He defiled an under age child and impregnated her in the process.
MoonKi : Just asking, do you think a Child Molester meets the demands of Chapter 6?
The DP cracked open some "extra-curricular" fur-burger? Good for him. And good for the country too: a wise man once remarked that a leader who doesn't have anyone to f**k will f**k his country. And there is plenty of evidence to support that view: in Kenya, just look at Moi.
On Chapter 6: As far as I can tell, it was devised to fill what would otherwise have been a huge blank space in the constitution. ("Practicalities" are irrelevant.) If one were to focus on the purported intent, the inevitable conclusion would be that The Great & Beloved Country (and Economic Powerhouse of East Africa, with SGR and Tablets for Starving Toddlers) is led, at all levels, by .... <think of a phrase that involves the extremes of "moral turpitude">
I have noted the various comments on age. In a properly-run country these might be relevant; as it is, Kenya is a country of thieves, scoundrels, and assorted criminals---from the top to the bottom---and it's been that way for a long time. On ding-dong matters, my secondary-school-days recollection is that some of the fiercest competition we lads had to deal with came from pot-bellied "Honourables" ... "sugar-daddies" then, "sponsors" today.