The post here by Monica Cellio, plainly says that community wiki is still owned by the poster.
Community wiki is the process of opening a post (question or answer) for community editing. Because they're designed to be collaborative, they stop earning reputation from the time they are given this status. However, those posts are still owned by whoever posted the first revision; the posts are linked on that user's profile, and that user will earn badges for votes, views, favoriting, and so on. Those posts are community wiki but not community-owned.
The comment by Shadow Wizard in the question referred also agrees to the same.
I think you have been confused by a very old information. The part you quoted was written six years ago when things were very different. Since then I'm 99.999% sure CW posts no longer owned by the Community account. – Shadow Wizard
However the FAQ on community user says that community wiki posts are owned by community.
How do Community Wiki posts work?
Community wiki posts work by transferring ownership of the post from the original author to the community. They make the post easier to edit and maintain by a wider group of users, but they do not contribute to any user's reputation.
The "ownwership" that Shadow Wizard and Monica Cellio are talking about is (in my opinion) in the real sense of the word, meaning the post belongs to them. I don't really know what the community wiki post is talking about when it speaks about "Ownership", but I think it is speaking in the same sense as above.
I want official clarification as to who owns community wiki posts. It would also be very very good if some experienced user edits the community wiki FAQ to reflect the official statement.