[Rest assured Sebastian knows perfectly well Lucifer is sensitive about that particular issue. It's the exact reason why he pushes:]
Oh, nothing can? Mean you to say nothing, or no one?
[There are literally only two people around who could stop Sebastian, and one of them was not in the immediate vicinity - that very much puts the responsibility on Lucifer. Yes, Lucifer should have kept holding on to Sebastian. How on Earth does their mutual lack of enjoyment of such a thing outweight the potential consequences of not holding on to him?]