There are two "Spotlight Suggestions":
- "Spotlight Suggestions" in Safari
- "Spotlight Suggestions" in Spotlight
Both query the same servers, both use the same name, and both return the same information.
A reasonable person might believe that, having followed Apple's instructions for disabling "Spotlight Suggestions" (the Spotlight kind), they'd disabled "Spotlight Suggestions" (the Safari kind) -- especially if you didn't actually see any suggestions appear in Safari (I didn't!).
Mark Rowe, Safari developer at Apple: "That’s probably a fair complaint." https://twitter.com/bdash/status/524005838743035904
There needs to be a single checkbox: "Do not share my Spotlight data with Apple".
There's already a single checkbox for "Diagnostics & Usage Data", and that should be respected too. The network query posted here is actually a search metrics POST, not a live search query, and it's used as metrics for local and remote search performance.
p.s. It was also just pointed out to me that, having selected a specific search engine, a user would not be remiss in believing that their searches would be sent to the only the search engine they had selected.