For the LLM-agent consumer, this baseline is good news: the agent grounding on cupertino's top-1 will always get apple-docs (the API reference) for any Swift-code-generation query that has an apple-docs answer. This is the intended bias.
For mixed-modality queries (an agent doing UX work, or generating SwiftUI code while also reasoning about HIG guidance), the agent would need to explicitly issue --source hig queries to discover design guidance — a behaviour the MCP server's tool surface would need to advertise so the agent knows to do this. Worth tracking as a separate concern.