Jim can't fathom why anyone would mind sharing a room with a doctor, but then again his idea of doctors is likely very different from Wikus's. He also knows Bones would never do anything to anyone if they weren't alright with it, so he feels completely sure about making the suggestion.

"You don't have to worry about that. I might call him Bones but you can believe me, he'd never do that. He'll sooner spend the good part of an hour listing out all the reasons why that's such a bad idea."

It's an ancient practice in their time, borderline medieval and barbaric. Jim's sure Bones would never go with that as a treatment option. He wouldn't even call it a treatment option to begin with.