I don't think you can stop players from interacting unless you pause the game or set them to something like a sleep status, or of course just tell them not to.
Yeah, I was mainly trying to think of ways to avoid repeating the scenarios that happened in the GM Mode Preview Stream with Mercer and company: players ignoring what you're saying and just running rampant, pillaging everything, etc. Was hoping for a more elegant solution than the awkward "Game Pause." But it'll just take some getting used to, I'm sure.
EDIT: Formatting
