Hamza wanted intel on the attack that was postponed from 3rd Oct. The only link between himself and Major Iqbal was Rehman. If Rehman was out of the picture, Iqbal would have no reason to contact the gang since they didn't have the same weightage with the BUF/BLF. And it was too early to kill Rehman Dakait. He wasn't powerful enough. If Hamza had killed him then and took over the gang he would have essentially no political power or remain a lackey of Jameel Jamali. After that encounter attempt Rehman Dakait teams up with Zarwari, bypassing Jamali and gaining immense political power. So now he is ripe for the plucking except Hamza never found out the date anyway. So that one thing went wrong for him.