Mujib was a traitor he shook hand with India against Pakistan in 1968, the case is known as Agartala Sazish, thus he could not be made pm.
The truth is that Yahya Khan played a very destructive role in 71 election, in West Pakistan bhutto was selected otherwise Jamat e Islami was in Majority and would have won the election, in East Pakistan the Awami league of Mujib used hooligans and rigging to turn the result in their favour, they did not let other parties to campaign and during and after the war raped and killed their opponents in hundreds of thousands.
All lies, Pakistan Army came to bring law and order which was destroyed by Awami league and Indian trained Terrorists known as Mukhti Bahni, many of whom were just Indian soldiers in different clothes.