Everyone of you can commercialize the PHP-knowledge he/she gained directly
or indirectly through this "global public domain project". Either you earn
money with php-programming, or you earn money with teaching, training and
consulting. Or you earn money with books and articles.
Whichever way you chose, you always contribute to the globalization of PHP.
That is not to forget that programming, teaching, training, consulting is all creating something new. Copying a part of the manual, adding some own content and selling it under your name on the cover is not comparable.
BTW I don't understand German, so I cannot comment on what was written in there...
Goba