I am not sure to whom Ruto turns to for political advice, but this fact is patently clear-- whether it's the U.S., Ghana, Zambia, Nigeria or whatever, generally speaking, Vice Presidents or its equivalent in Kenya masquerading as DP do not normally succeed the outgoing president-- unless the incumbent president dies in office. There are, of course, exceptions to the rule.
Politics 101: There are no I.O.U's in politics unless you really owe someone....