I don't I agree with the author. What is sexual privacy? Should it be any different from any other private matter or image that I do not want to be shared publicly? How would it be enforced? On a pseudoanonymous app, it would likely be the provider that would be held accountable, and made to surrender the user's information to the authorities. Would providers be able not to give that information? Should they be made to collect it just in case? These are unfortunate incidents. However, the resulting dissemination is fallout from a crime. The persons that created that fallout by stealing the images can be prosecuted on a clear basis. Trying to punish those that posted, or shared, or upvoted, or liked, the images would likely do more harm than good.
It's so easy to point fingers at all the forums and online-sites sharing pictures, the author is being naive in thinking new laws are going to stop people from sharing available information. And "sexual privacy" laws cover a different issue, they're designed to close a loop-hole where someone obtains sexually explicit images legally and then shares them without consent.