Two facts support HSM's decision.
1. The fact that Deni became a Presidential candidate makes him a foe rather than a friend. If Deni's desire was all along to help HAG candidates reach Presidency and prepare himself for Prime MInisterial role, then HSM would have been the one at fault here. But that is not the case.
2. The fact that Farmaajo brought Hassan Ali Khaire who is not from the traditional branches that assumed the Prime Minister, then that gives HSM the freedom to also bring someone who is not from the traditional recipients of the Prime Minister's role.
All said and done, HSM is not the first to break the tradition but rather just following the lead by the D-clan's.