I have specifically avoided giving any motive. While not all clergy are saints, even if Archbishop Vigano is shown to be factual wrong about their being sanctions, then the more charitable interpretation would be that he genuinely believed their were sanctions. What we want, our bias, can skew our perception and memory. It also can make a letter like he wrote factually, but honestly, wrong.
Take the case of Edward Peters. He is an expert in canon law and makes a compelling case that canon law encourages a bishop to resign if he becomes ineffective, even if through no fault of his own. However, surely he, as a canon lawyer, knows that canon law does not apply to the pope, just like retirement age for bishops do not apply to the pope. Would he have missed adding this in if he was not of the opinion Pope Francis should resign, if it is found that there were sanctions?
And yes, I think he is totally all wet on his suggestion that St. John Paul the Great should have resigned. We would be poorer for it. Of all he did in the last few years of his life, nothing was more important than the saintly example of the value of the elderly in society. They can remain productive far longer than our youth-oriented culture acknowledges.