I haven't read the whole thread, so my reply may be way off.
I'd say in defense of the people who don't want to RP with newbies that it's difficult to tell which of the newbies are worthwhile and which aren't. I mean that from the point of view of who's going to stick with the game and who isn't. If you look at the number of accounts that have been created on PS vs. the number who ever really played the game for a meaningful amount of time, you can see that the vast majority of newbies aren't going to be around long. Unless you're an abnormally social or cheerful person, it's hard to want to be friendly to every single person who comes along despite the fact that you'll probably never see them again.
Now, you could argue that people being unfriendly is one of the reasons that so many of the newbies don't stick around, and that could be partly true. On the other hand, look at the sheer number of people who've tried PS out, and then take the number of people who actually left the entire game because one or two people didn't have a sunshine-and-daisies attitude toward them, and the percentage will be tiny. "Trial by fire" isn't nice, and it does have the possibility of killing off a small amount of people who might've been worthwhile members of the community, but on the other hand it's emotionally, mentally, and chronologically efficient.
That said, I'm not condoning people being jerks to newbies, I'm just saying that maybe it's not quite as horrible and community-destroying as is generally thought by the people who have the energy and desire to be nice to every single person, and maybe it's somewhat understandable.
Personally, my approach is generally to just be noncomittal. If I'm in a mood where I don't really want to pander to a newbie, then I'll be cold, without being mean. I'll reply to them, but not in a way that invites conversation (easy when RPing Phinehas). That way they leave me alone, but hopefully aren't offended personally.