I’m not sure what defederating from them solves in regards to this topic. If they wanted Lemmy, Kbin, & Mastodon’s data, they could always just set up another instance with a different domain name and not publicly announce what that domain name is, and we would have no idea who to defederate from. Or they could just scrape the data from the web page, no federation needed.
I don’t want to see their content, which is a valid reason to defederate (or block, if that were possible at the user level) imo. But defederating because we want to stop them from getting our data is not even slightly effective, so I think it makes an unconvincing argument.