I’m just asking, was Data pulling the trigger to shoot Saul Rubinek when they transported him?

Of course. You think a weapon is just going to discharge by accident in Data’s precision grip?

As a transporter chief, I can say with absolute certainty that Data rightly pulled the trigger and killed that son of a bitch murderer the positron flux of the cascade resonator must have caused feedback during the transport cycle and caused the transporter system to falsly read a weapon discharge. It happens with these old Varon disruptors.