[He chuckles softly in response, entirely pleasantly.]
In such a scenario I would only ask that you please relay the warning to the others here.
[Such a philanthropist, that Sebastian. Really, he just wants to know if he can leave Ciel to his pool shenanigans or if he needs to swoop in to prevent consumption of questionable sweets. Although:]
The taste, at least, is fine, but I suppose that doesn't rule out the risk of side-effects.