The UPM guidelines are, we assume, unremarkable.
Contributors who are prone to racism, sexism, homophobia and gratuitous verbal violence are unwelcome.
We can't, realistically, insist on rationality at all times but we do request civility.
Obscenity: tricky, as assorted critics, censors and centurions have discovered. Flaubert, Baudelaire, Lawrence, Aubrey Beardsley, Hubert Selby Jr., Nabokov, Rabelais. And the films. And the paintings. Contributors may also be significant artists—but probably not. So, if it offends our eye, we pluck it out (not the eye).
In short, accepting the guidelines simply means agreeing to conduct yourself in a civilized manner, which you already do. Don't you?