As undutiful is defined by "non dutiful", and "dutiful" is:
"filled with or motivated by a sense of duty"
Yes, according to the dictionary definition, opinions can be motivated by the sense of duty, or filled with this feeling, emotion, opinions can be wicked, wise, or anything that the man who bears the opinion is. An object can't be wicked or wise, or anything a man can be, but an opinion or an idea can.
The opinion can be intellectual, or the emotions and feelings of the man. Even if it's not common, there's nothing, logically, preventing this sentence to be forged and said I believe.