RV Pundit, the reason is simple. The PS has the ear to State House. No civil servant can show such arrogance without the backing of SH. He knows who has interest in this whole deal and I can assure you all such deals in Kenya have a local broker who is politically connected and with at least 10% of the deal in his pocket.
Same thing happened at Mafya House where the PS ignored instructions from the CS and there were no consequences. The Kenya govt is so structured that all powerfully ministries are either led by people from Central or in the case where this is not the case, the PS is from Central.
CS Wamalwa is a flower girl and one sees that he does not even have his heart in that job. He wants to go back to politics but has no idea where to start. The CS is just using Wamalwa's weakness to do his own thing.