[The creeping suspicion that Sebastian might not be in a fit state later to go out and gather additional food, should it turn out they end up being snowed in for longer than anticipated, that's what's gotten into him (and the only reason Sebastian even considers the possibility that he's not completely invincible is that he's been through this whole sickness thing once before. character development!!).
He did take the food-wasting creature into account (with the appropriate amount of sighing). It's just that now Lucifer's hedonist share has been re-branded "extra emergency stock".]
Practicality, sir. [...Ugh. This would have been a cleverer answer if Sebastian could only think of something clever.]