More generally, semantics of the posteriors, and of probability in general, comes from the semantics of the rest of the model, of prior/state space/variables/etc. It's incorrect to attribute any kind of inherent semantics to a model, which as you note happens quite often, when frequentist semantics suddenly "emerges" in probabilistic models. It is a kind of mind projection fallacy, where the role of the territory is played by math of the mind.
To return to something we discussed in the IRC meetup: there's a simple argument why commonly-known rationalists with common priors cannot offer each other deals in a zero-sum game. The strategy "offer the deal iff you have evidence of at least strength X saying the deal benefits you" is defeated by all strategies of the form "accept the deal iff you have evidence of at least strength Y > X saying the deal benefits you", so never offering and never accepting if offered should be the only equilibrium.
This is completely off-topic unless anyone thinks it would make an interesting top-level post.
ETA: oops, sorry, this of course assumes independent evidence; I think it can probably be fixed?
I've often had half-finished LW post ideas and crossed them off for a number of reasons, mostly they were too rough or undeveloped and I didn't feel expert enough. Other people might worry their post would be judged harshly, or feel overwhelmed, or worried about topicality, or they just want some community input before adding it.
So: this is a special sort of open thread. Please post your unfinished ideas and sketches for LW posts here as comments, if you would like constructive critique, assistance and checking from people with more expertise, etc. Just pile them in without worrying too much. Ideas can be as short as a single sentence or as long as a finished post. Both subject and presentation are on topic in replies. Bad ideas should be mined for whatever good can be found in them. Good ideas should be poked with challenges to make them stronger. No being nasty!