Whether a belief is wishful thinking is inherently an assertion about the mental state of a person. It is meaningless to say that you should examine the assertion instead of the mental state, since the assertion is an assertion about the mental state.
I don't know about that. Merriam Webster defines wishful thinking as:
an attitude or belief that something you want to happen will happen even though it is not likely or possible
So if my calculations are accurate, per Merriam Webster's definition, I have not engaged in wishful thinking.
Another month, another rationality quotes thread. The rules are: