Another reason to dislike that warband. Contradictory rules are, alas, a GW staple. Along with incomplete or incomprehensible ones. At least they are consistent.
I am intrigued by your assumption that the author's error is writing the last part of the first rule as opposed to screwing up the rule for immune to psychology. It took effort to make either mistake and the wording of immune to psychology is completely different from the Mordheim rule book's wording...