Why did Sentinel Prime let Optimus live in Transformers Dark of the Moon?
August 13th, 2011
Back soon after Sentinel betrayed the Autobots, Sentinel activated the 5 pillars for the first time over that pond in Washington D.C. Anyway, Optimus tackled Sentinel and had a little brawl, and Sentinel held his sword to Optimus’ throat, but decided not to kill him. He told Optimus that "he’d understand why he didn’t kill him in the future." I never understood why he let Optimus live there because I don’t think the movie ever explained what Sentinel meant by Optimus understanding it later.
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The only thing I can think of is that he accomplished his mission and opened the space bridge to bring more Decepticons from the moon to Earth. Just like when he tore NEST headquarters apart after destroying Ironhide, he was done when Mearing let him get the five pillars out of the main vault. He is about killing to attain his goals but once he accomplishes them, he is willing to concede. When Optimus shot the control pillar from the building, that set Sentinel off to where there was no mercy in him to hold him from killing Optimus.
As for what Sentinel said to Optimus, I guess he said that because he wanted Optimus to see what he was planning to do, which was bring Cybertron to Earth.
i thought the same thing and maybe its cause Optimus has the matrix, and if any of the Cons got killed, then Sentinel could talk Prime into(or make) reviving them. OR, he wanted to have him become a slave or have a summer BBQ party with him and MegatronXD
I think it was because he didn’t really want to kill him in the first place. He said that it was for the survival of Cybertron and I think that Sentinel wanted Optimus to see the "wisdom" in his decision. He believed that joining forces with the Deceptions was the only way that their race could survive and rebuild Cybertron.