That story is fake.Sharif was arrested long time ago and was left loose to enable peace negotiation with the Islamic court... he eventually worked with the govt to become the president of somalia...he parted ways with alshabab and attempts on his life were numerous but he survived ...eventually he was defeated in an election just the other day.
KDF did not train alshabab it trained militants who were allied to Makobe a former alshabab commander who shifted his alliance to amisom/KDF He is now the self appointed president of Jubaland with the capital being Kismaayo.
During the attack there was a leak to the effect that the leaders of the attack had trained using the westgate blueprints In a US state...the three leaders then using their local contacts were able to get reinforcement from somalia.
According to intel from captured Amniyaat operatives (an alshabab intelligence unit) the cells operate independently and do not know each other.Operatives answer directly to Godane this system (horizotal sytem) of reporting reduce leakages incase of capture.Membership to the Amniyat is strictly restricted to Somalis with a linage that can be traced.
Given the structure of Alshabab and their continuous threats I am positive the story is a fiction since Alshabab would not risk putting their efficient intelligence unit at risk.
'......to the acknowledgment of the mystery of God, and of the Father, and of Christ; 3 In whom are hid all the treasures of wisdom and knowledge.' Colossians 2:2-3