I looked it up on the internet and found a site called "Catholic Answers". It says that the church cannot change "teachings" as in doctrine. They can change ("loosen") disciplines. See site below for examples if you'd like.
I guess it depends on whether a stance on homosexality is a doctrine or a discipline. I was unable to find cite that states whether the Catholic Church categorizes their stance on homosexuality as "doctrine" or "discipline", but I would be surprised if it is considered a doctrine.
http://www.catholic.com/quickquestions/can-the-church-change-its-doctrines
Here is what the catechism states.
For the purpose of this argument the catechism suffices
It doesnt take a canon law expert to know that the pope was taken out of context and off guard on the plane ride home from wyd and that he has not changed Church teaching whether its dogma or not
It is a sin to act on sexual temptations that are disordered and out of the context of marriage
That’s all
The pope cant change that like a mayor changing a city ordinance as the article hopes