Matona was suspended in March 2015 for reasons he said he could not understand, but he surmised that his position as CEO did not fit in with the plans of the board.
He said his suspension by a new board reportedly packed with Gupta-linked members came as "a complete shock".
Matona was replaced as CEO by Brian Molefe, who was accused in former public protector Thuli Madonsela's State of Capture report of having facilitated the awarding of lucrative supply contracts to Gupta business allies.
Matona, who was previously a director-general of the departments of trade and industry and public enterprises, challenged his suspension in the Labour Court and CCMA, but later abandoned the case.
"I chose to leave that sordid and sorry episode behind me to continue with my life," Matona said.