They don't use non-standard records; if your resolver protects your privacy by not sending them your IP, they will intentionally return bad records specifically to fuck with you.
They stated they need it to stay in line with the law but they can do that with things like the user's IP. To go that far to insist on getting a specific type of user data is sketchy.
See https://news.ycombinator.com/item?id=21308564 and https://news.ycombinator.com/item?id=23316085