Yeah, but
Orvas Dren is also the head of the CT, and only he and 2 others are CT - most of the other members of the council aren't involved with the CT.
In fact, the journal entry (sourced from
UESP) states that
"Duke Dren told me that I must win control of the Camonna Tong from his brother Orvas Dren before I can be the Grandmaster of House Hlaalu in anything other than name only." I assume this is because
Orvas Dren controls Velanda Omani and Nevena Ules, and so can sway the council easily.
Just my take.