According to this you can copy stuff onto it. I assume you've tried to see if you can copy off? If not, then there is probably no way to extract the audio, short of recording it as it plays.
I was only able to find a couple episodes online. One on someone's google drive and a few in the wayback machine, all from this thread
edit: if playapod has an option to store files on an sd card, that's usually stored unencrypted. (on android anyway...)
edit: wait iphones don't even have sd card slots, right? lol
Actually there might be a whole bunch more in the wayback machine. (though still not that many) here
Just sort by mime type and check out audio/* for items of interest