It may not matter whether there is gold in them thar hills, but it does matter what the oracle says. So I think you have misstated P's utility function. P wants the oracle to tell him the gold exists, that is his utility function. And realizing that, you cannot say that it doesn't matter what the oracle really tells him, because it does.
I don't think P's hypothesized stupid reliance on a lying oracle binds us to ignore what P really wants and thus call it only a state of mind. He needs that physical communication from something other than his mind, the oracle.
I am stipulating that P really truly wants the gold to exist (in the same way that you would want there not to exist a bunch of people who are being tortured, ceteris paribus). Whether P should be trusting the oracle is besides the point. The difference between these scenarios is that you are correct in believing that the people being tortured is morally bad. However, your well-being would not be affected by whether the people are being tortured, only by your belief of how likely this is. Of course, you would still try to stop the torture if you could, eve...
I figure morality as a topic is popular enough and important enough and related-to-rationality enough to deserve its own thread.
Questions, comments, rants, links, whatever are all welcome. If you're like me you've probably been aching to share your ten paragraph take on meta-ethics or whatever for about three uncountable eons now. Here's your chance.
I recommend reading Wikipedia's article on meta-ethics before jumping into the fray, if only to get familiar with the standard terminology. The standard terminology is often abused. This makes some people sad. Please don't make those people sad.