I think those times might be wrong (I'm thinking through a head-full of snot), but I think the point was, if she ate two hours before, a fair amount would remain in her stomach. If she ate six hours before (so at 9PM), you would expect 10% left, which would mean she had to eat 2lrs worth. If she ate earlier, at 6 or 7, it would go up to about 4lrs.
Of the thing that can slow gastric emptying, Nel discounted smoking and alcohol. There was some issue about a fatty meal, which takes longer. Nel relied on the style of these two - an athlete and a model, to suggest that they didn't eat a fatty meal. I don't know why he didn't list what she ate - he must know. Diet pills and drugs weren't mentioned today. That I can recall.
I hope that my maths is right there - if not, please blame the snot.
And welcome, Mortal.