OK, we can decide at that time whether we want to give up what is desirable and etc. in exchange for what is right, but in the meantime I might well be satisfied by that result

No, once ostensibly-Friendly AI has run CEV and knows what it wants, it won't matter if we eventually realize that CEV was wrong after all. The OFAI will go on to do what CEV says it should do, and we won't have a say in the matter.