because it is one more in the list of people not happy about the decision, as were several people/ groups mentioned in the article.
"Not Happy" is kid of vague. Since I don't know your wife's boss, I wouldn't know if it was one more to the list or not.
Is your wife's boss gay? A feminist? Does he/she favor married priests, female priests, homosexual priests? Is he/she a fan of liberation theology? Marxism? Relativism?
What specifically about Pope Benedict XVI makes your wife's boss unhappy?