If nothing else, the time Severus spent aboard the Barge made him particularly superstitious. He doesn't say he's bored for fear that a flood - or, in Baedal, something nastier - might occur, and he never makes a statement remotely resembling the one Lucius just has.

Because inevitably, hoping aloud to keep someone away only results in drawing them in. Sirius Black, for example.

He refrains from comment, however. He doesn't know what it is Lucius might want; perhaps he misses Draco. Perhaps he, like Severus and Martha, might view Baedal as a city with some (some) potential for a life. Or perhaps he wants to keep his family as far from here as possible. 'Some potential' does not a suburban paradise make. Instead, he decides to redirect the conversation back to Narcissa Black. "There is little harm in telling you now that she purchased sleeping potions."