Priests using chastising and guilt to get people to donate is an initiation of force, it plays upon irrational people's fears of eternal damnation/smiting "God" to coerce them.
Stef's appeals for donations don't initiate force.
If I went to a restaurant and the manager States "if I enjoy the meal, the right thing to do, would be to pay the chef for his efforts", the manager is not forcing me to pay or implying that if I don't pay, bad things will happen, he is simply appealing to my integrity.
Stef puts out these podcasts for free, it takes time, effort and money to do so, if a person has the means, they "should" at least, "buy the philosopher lunch", if they're able they will hopefully support the show.