"The only involved I've got any intention of getting is asking where your medical kit is, if you come back bleeding." That's honest enough, anyway. "You don't need an extra element you didn't account for in your plan. It's just going to make it more dangerous for everybody."

That said he will likely position his ass somewhere close enough to monitor from out of the way. Intended involvement is not the same as 'willing to become involved'.

And - "I'll sleep on the couch. I just barely got used to sleeping in a bed before everything went to hell, anyway. Kept winding up on the floor because I felt like my mattress was trying to swallow me."