It’s a complicated wrinkle to explain. Yes, the amendments happened during Ershad’s regime, who took power in a bloodless coup. Calling it a dictatorship is a strech: Ershad tried to have elections, in which one of the two major parties participated. More importantly, since Ershad left power in 1990, nobody has moved to change the constitution back, Islam plays a bigger role in politics than ever, and and 82% of the country (according to Pew polling) suppoets making Sharia national law.