It's more personal friendship - btw Ruto & M7. 2007 was wake up call for M7 to keep closer tabs on Kenya - and I think he realized that Uhuru like Kibaki was a joker. M7 takes leadership role very seriously - and security very seriously.
Now when it come to Uhuru - it started in Feb 2016 - Museveni believes KDF drown his expensive three Mi-24 helicopters in Mt kenya.
Kenya was apprensive about M7 ambition to go to SOmali and acquire the Sukhois.
Did Kenya drown the M7 three Mi-24s heading to Somali in Feb 2016 - or deliberately misguided them to hit Mt kenya.
https://www.monitor.co.ug/uganda/special-reports/tragedy-on-mt-kenya-as-ugandan-choppers-crash-1663326What is obvious is that come Aprll 2016- Uganda cancelled the oil deal and re-routed to Tanzania.
This around the same time that Museveni and Ruto started building their friendship...Ruto was campaigning for M7 in Sabaot and has
subsequently been donating his choppers to Uganda.
Museveni appreciate the role Moi played in his quest for power.
M7 like Lee Njiru says - use to run his militia - right from statehouse - with Moi providing tactical support.
Museveni likes Kalenjin - even in Uganda - he has many in his private security.
Museveni hates Luos.
So it's easy to see why he likes Ruto and hates Raila.