After watching Five Servos of Doom again. Yoketron tells Prowl that when his time comes he will understand "not to sacrifice a piece of the future to bring back the past". Now we know Prowl is going to die saving Prime, I think. So what if Prowl is as old as Ratchet (judging by Yoketron's Project Omega comment) and realises that Prime is destined to lead the Autobots. the scene could be something like Prowl and Prime been trapped and only one can escape. Prime insists Prowl escapes because he is prowl's commanding Officer. but Prowl realises Prime is destined to lead the Autobots hence sacrifices himself so Prime can live, therefore understanding the whole not sacrificing the future stuff.