"He won't mean it in a bad way." And Yuya's certain about this because he knows his relationship with Childermass, and he's seen the more private parts of that (not those parts). And Yuya hasn't thought about running around telling people, because it's just not the most important thing. But, well, focusing on that little moment of normalcy is a little anchoring, in that maybe he can use it to convince himself they'll definitely save Lambert.