Why did he almost go postal on this Senator? Frankly, it's pretty easy to explain.
Per DSM-5 Uhuru Kenyatta would easily be diagnosed as mental. Maybe it's the denuding effects of too much liquor.
Generally speaking, people who are wont to respond reflexively and with anger when put on the spot - for even the most mundane things - have low levels of self-control and are also more prone to criminal behavior. Check out the typical Uncle Vinny of Mafia lore or, say, those murderous gang-bangers killing each other on the streets of Chicago.
In short, Uhuru is an impulsive man-child -- kind of like our very own DJT.
Oh, as for Raila? Ah! The fella is impetuous.
Kenyans, you're spoiled for choice! Yeah, quite the embarrassment of riches you have there folks.