"Yeah, now that you mention it, I'm gonna have to insist. Let's take the food upstairs." He'd also rather not cause any trouble, and the way people are staring, it's best for the two witchers to make themselves unseen. He waves to the serving girl again and asks her if she can have some of the maids change the water in his bath. And he insists they can take their own meals upstairs, which makes her look quite relieved to not have to perform all the usual small niceties for two guests more beast than man.