A scholar gives three reasons why the Sulu Sultanate cannot assert sovereignty over the state.

“Neither the Sulu Sultanate nor the Filipino government has a claim over the North Borneo state,” said DS Ranjit Singh, an expert on Southeast Asian political history who is now a visiting professor at Universiti Utara Malaysia.
“The moment we negotiate with them, we compromise our sovereignty,” he said in a talk at Universiti Malaya today.
He said the Sulu claim was futile for three reasons: the Philippine government’s predecessors renounced all claims over the state, the Sulu court has never administered the state, and the people of Sabah agreed to form Malaysia.