Recently moderators have twice deleted some highly upvoted comments that point out some false claims an answer makes. The main comment was extremely well-received, as comments that get 30+ upvotes are rare (the answer also has 21 downvotes, indicating regular users see major problems).
This is also exactly the kind of things comments should be used for.
Use comments to ask for more information or suggest improvements.
Obviously an answer with false claims has room for improvement. Even if the author choose not to (perhaps because they are deliberately spreading lies), that comment can help future readers who might be deceived by the post.
It's also not an extended or side discussion, so the move-to-chat comment doesn't make sense.
Deleting such comments when they are being used as directed makes no sense. If you are going to delete something, you should delete the answer, unless those are held to lower standards than comments here.
(To make the situation even more strange, the moderator decided to send some cryptic pre-writen moderator message over this.)
Looks like moderators actually gave the user, who is likely trolling, exactly what they wanted all along.