I don't get why people think he just gave up and was tricked. First off, he didn't give up. He realized that even if Hitler wasn't killed that night, the Germans were going to lose the war. Therefore he was smart enough to know that he had leverage to try and work out a deal to be on the winning side, something he most likely wasn't ever going to have.
Second, we have no reason to believe it was a complete trick. All that happened at the end was he got the swastika carved into his forehead, but it never said whether or not he was granted all his demands. I personally believe that he was still granted his more reasonable demands and was not killed or tried for his crimes, since he did in fact win the war for the allies.