We had a similar situation with a rum custard cake. It was bought for a birthday the next day. Cast of characters: Family members A, B (under the weather) , C (a sibling) and me.
Family member A said to me "I want to cut the cake, Family member B isn't feeling well enough to eat cake, no sense in saving it for tomorrow'.
I said 'No, let's wait until tomorrow, Family member B is now sleeping, hasn't seen the cake, and may feel like having some tomorrow'
A goes to Family member C and says that *I* am dying for cake and absolutely want some tonight, 'and B doesn't feel well enough anyway'. C doubts it and tells me. In the meantime, A takes the cake up the hall to B to show him, then cuts it "He saw it, I'm cutting it". A had a piece of cake, it was offered to C and I but we both declined.
Some people want their cake and they want it NOW, even if it's not theirs. Some people get really weird about food.