That was why Mr Igathe was brought in to lend an air of balance and respectability to the ticket, and also stand as the face of modern corporate governance by which the city will be run.
The subtle message being sent out was that Governor Sonko would be political head of the city, but with Deputy Governor Igathe effectively in control of policy, planning and development.
Mr Kenneth in his announcement took a clear dig at that, dismissing as a big lie, any suggestions that a city as important as Nairobi could be entrusted to a “figurehead” governor while somebody else ran the show.
A big unanswered question was whether it would be possible to shackle Mr Sonko, once he was safely settled in office, especially as the Constitution does not contain any job description for a deputy governor who can only perform the duties assigned to him by the governor.
Mr Igathe would need a strong hand indeed to dissuade Mr Sonko from some of his more outrageous schemes, such as proposals to turn Uhuru Park into a giant matatu stage, and open up the central business district and the Nairobi arboretum to hawkers.
That right now might be the least of Jubilee’s concerns as Mr Kenneth’s entry upsets the equation.
For one, his bid for governor dilutes Mr Igathe’s designated role of lending respect to the Jubilee ticket.
Mr Kenneth will appeal to the very same constituency that Mr Igathe was supposed to offer comfort to.
There is the elite repelled by Mr Sonko’s antics, and also concerned over his lack of coherent plans to restore the city to its former glory.
Mr Igathe’s selection was also intended to appease Nairobi’s powerful Kikuyu mercantile and political establishment that had rallied around Mr Kenneth, in whom they saw not just a prospective County governor, but also a future contender for State House once President Kenyatta bowed out.
There was also the loss of one of the community’s veteran Nairobi political kingpins, Starehe MP Maina Kamanda, who was beaten to the Jubilee ticket by a Sonko protégé, musician Charles Kanyi, alias Jaguar.
Mr Kenneth took potshots at both Governor Kidero and Senator Sonko during his announcement, and like nearly all Jubilee nomination losers who turned independent affirmed his support for President Kenyatta.
He now has the task of proving a point: that he was indeed rigged out at the Jubilee primaries, in which case he will be aiming his bullets more at Senator Sonko.
That bruising battle for the same core bloc will be keenly observed by Governor Kidero who stands to reap from the split Jubilee base.
If the numbers by which Mr Sonko won the Nairobi Senator’s seat in 2013 and the adulation he receives from the Nairobi masses are anything to go by, he might still be the favourite, but the new development complicates matters.
Meanwhile, there will be an interesting sub-plot in the battle for Nairobi: whispers that Mr Kenneth was setting the stage for a presidential bid in 2022 had attracted the attention of Deputy President Ruto’s supporters.
They had taken note of signals that powerful businessmen and community leaders under the aegis of a Mt Kenya Council of Elders were plotting to trash the Uhuru-Ruto power sharing and succession pact, and place one of their own to carry their flag.
Indeed in the wake of the Jubilee nominations, a group of prominent losers in central Kenya have re-grouped to blame succession politics for the defeats, pointing the finger at Mr Ruto’s allies.
This might turn out to be more than just a battle for Nairobi.
This article was originally published in the Daily Nation on May 20, 2017.