Yes, a LaunchAgent based solution requires a logged in user because the iOS Simulator requires an actual GUI context. We (at Bitrise) experimented with a lot of solution and configuration but couldn't find a solution where you don't have to log in with the user on the GUI.
Btw you can find our solution on GitHub, might be helpful if you plan to do something similar: https://github.com/bitrise-io/xcodebuild-unittest-miniserver