Perhaps they want the prohibition on using the site content for AI training to be considered based on something other than their ownership of it, like bandwidth usage or users' rights
They will get paid to share our (your) data and they will use the money for infra and new yachts.
Indeed, but I'm speculating that they do that without owning the data or even claiming to. That's consistent with the article, but I haven't read the other relevant documents. Maybe they have a license to use the data. Maybe the license allows or requires them to try to restrict others' AI training, regardless of their non-ownership of it. Maybe that serves multiple purposes, in which case they could point to whichever shows them in the best light.