I don't believe the agent's testimony. The way he expresses verbatim sounds like a coached response typical of legalese confessions.
Given the legal precedence for tampering, it would be difficult to prove otherwise. There's just no need for Ruto's team to prove that the elections were fair and credible because that won't do any favours for them if there's a re-run and Azimio wins.
Also the fact Chebukati refused to reach consensus with colleagues is sufficient enough to demonstrate the need to nullify.
There should've been a re-run as normally the case with low voter turnout and non-consensus. Even with a re-run Chebukati could've announced Ruto as the winner but instead Chebukati fed ammo to Azimio.
Does he want the IEBC to be disbanded so he can flee with the money and let someone else declare Azimio the winner?