However the ambiguity and the context make this statement imprudent in the extreme, esp. in a published Vatican document.
I say "imprudent". I would even say "harmful". I don't say "corrupt", because it is not a blessing of shameful lust.
His transparent attempt to incrementally legitimize relationships based upon mortal sin by claiming that such arrangements possess an incidental good is a contradiction of Catholic moral teaching. He is, in essence, proposing that an evil tree can bring forth good fruit. Suppose he made the same positive claims regarding adulterous relationships? Don't adulterous couples also share "luv" and friendship and so forth? How about gluttons? Eating sustains life, after all, so food might also be characterized as a "precious support in the life of the glutton", right?
Only a corrupt perspective would lead someone to claim that elements of goodness exist in the midst of that which is fundamentally evil.