By the time one gets to be pope, I would expect he'd know the 1st Commandment. I would expect he'd know that it is a sin to encourage sin.
The event mentioned in the above article is the entire message of the late Holy Father's pontificate come to life. Assisi I&II were not two "blunders" in an otherwise traditional, orthodox pontificate. He participated/hosted many, many similar events over the last 26 years.
And if JPII did not think the Cdl was guilty of general heterodoxy (made evident by getting the red hat and never having been disciplined), who are any of us to say otherwise?
I think that both John Paul II and Mahoney got ecumenism wrong.