[Y]ou have described the meta expected value of P...It seems to me that you have made excessively harsh criticism against those who have made correct statements about P itself.
See my other comments. In my opinion, the correct point of view is that P is a variable (or, if you prefer, a two-argument function); the “correct” statements are about a different value of P from the relevant one (resp. depend on inappropriately fixing one of the two arguments).
EDIT: Also, I think this is the level on which Bayesian Bob was thinking, and the critical comments weren’t taking this into account and were assuming a basic error was being made (just like Rational Rian).
See my other comments. In my opinion, the correct point of view is that P is a variable (or, if you prefer, a two-argument function); the “correct” statements are about a different value of P from the relevant one (resp. depend on inappropriately fixing one of the two arguments).
EDIT: Also, I think this is the level on which Bayesian Bob was thinking, and the critical comments weren’t taking this into account and were assuming a basic error was being made (just like Rational Rian).