Ah. Naturally - his training regime must be demanding. It would not be mine neither my master's intention to steal you from him.
[I mean, Sebastian cares 100% about Ciel's training and 0% about Yuuri's, but in the interest of getting Ciel a coach at all...]
The document [he indicates the folder he's still holding] might look intimidating, I realise, but I certainly understand that any lessons would have to happen at quite possbly very long intervals. Your own student takes precedence, of course.
[Sebastian really is not dense about human emotions. But, see, he's met Yuuri once and deemed him a hapless, neurotic doofus, not to mention Sebastian and Victor's interactions have been nothing but professional. It makes much more sense to assume Yuuri worries about his own training suffering?]