+1
Yes in films the good guys sometimes have to kill the bad guys (or allow them to die). It happens. It even happens in most Disney animated films! But shooting a defeated opponent, and one that was causing no trouble until you showed up to kill him, isn't what you expect outside a film about the Punisher.
Freedom is the right of all sentient beings, right? Someone said that once. I thought it was Prime. I prefer to believe that the robot Prime shot in the head was just another of the dozens or more mindless drone constructicons, like the ones that appear later, rather than a living sentient Transformer.