He can't help but notice the irony in being told all this while also being slammed into the ground repeatedly. Please, where is the robot aspirin. This is far too much blunt force trauma to the head in such a short amount of time.

Regardless, he can't have gone through the sound ass reaming at the hands of Megatron and this right now without feeling a thing, everyone has their limits and Sentinel can tell when he's pushed his too far. He's far from being anywhere near what Optimus wants, but right now there's a multitude of factors piling up on each other and self preservation outweighs his (rather wounded) pride and ego.

Releasing his grip on Optimus' arms, he dims his optics a touch. The one that wasn't already shitting out, anyway, "You're-- right."

A puff of air escapes his vents and he ceases all remaining attempts to struggle against Optimus' grip.