So the AI is not an expected utility maximizer?

It's an expected utility maximizer, but it considers the expected utility of its decision process, not just the expected utility of individual decisions. In a world where there exist more known liars than known superhuman entities, and any liar can claim superhuman powers, any decision process that allows them to exploit you is of negative expected utility.

It's like the professor who in the example agrees to accept a delayed essay that was delayed for the reason of a grandmother's death, because this is a valid reason that will largely not be exploited, but not "I wanted to watch my favorite team play", because lots of others students would be able to use the same excuse. The professor's not just considering the individual decision, but whether decision process would be of negative utility in a more general manner.