Nikam conceded while arguing before TADA court Judge G A Sanap here that the case did not fall in the "rarest of rare" category. Hence, the prosecution was seeking life imprisonment for Siddiqui, he said.
The court has already sentenced gangster Abu Salem and his driver Mehdi Hassan to life imprisonment in this case.
Siddiqui's trial was separated as he turned approver, but later, he was declared a "hostile witness" by the prosecution during his deposition.
The TADA court convicted him last month.
Like Salem, Siddiqui was also an accused in the 1993 Mumbai serial blasts case. The TADA court sentenced Salem to life imprisonment and Siddiqui to ten years in jail in that case yesterday.