It WAS to invite shadowbanned sites that they don't acknowledge exist ... why? Is there some other euphemism that they use to describe these sites, and that would make some sense as a group of people to give special attention to?
Unfortunately, many legitimate niche websites were demoted by this update. Google's Webmaster outreach team (primarily Danny Sullivan, also known as "SearchLiason") has been in contact with people running such legitimate websites.
This event was supposed to bring such people together with Product Managers and Engineers at Google.
Someone from the data science side at Google, who is probably very far removed from the actual ranking algorithm, said that there was no shadowbanning of domains. That is, of course, total crap and probably just the result of some misunderstanding of what banning, demoting, penalizing, etc., means to different people.
The people at Google who actually work on communicating to webmaster never said there was no shadowbanning.