Genuine question: if the LLM possesses the ability to use Secretive to retrieve secrets are you not back to square 1? I'm not familiar with Secretive but if it's just another way to store secrets that's not enough. For proper security the LLM needs a black box intermediary to do anything privileged. I don't know what that looks like in terms of software.

Or better yet it needs dead-end privileges with a system and data that doesn't matter.