The solid running theory on the 'boop' involves the restriction put on Erfworld during book 1 for its run on giantitp. It is a known fact that Rich does not put any colorful language into his books and other website materials and it is strictly enforced on his website as a 'vulgarity free' webcomic. There have been many commments on this before and this was Parson's expression of breaking free of that restriction. Made for a good gag through out the book on why the erfworldians understood the 'concept' of the boop but not its meaning. - Do not take this for canon but a huge tinfoil hat therom :0
Well, yeah, that's obviously the out-of-story reason for why the boop filter was there and why it was only broken at the end.
But it was worked in as part of the story - so there's also an in-story reason and mechanic for how and why it works the way it does.
i think where it is part of the story is Parson just like he has intended in his own turn based game ..
is breaking the world to win.
he stated that he created a game you couldn't win within the rules
so you had to out smart the world of the game to beat it ..he is breaking erf world
while erf world is trying to break/mold him...
i say go back to the initial spell cast by wanda and see how the world is trying to conform Parson to the spells ideal. both physically, magically and mentally
and in the end it will be a mutual relationship almost parasitic.