I cannot believe you are actually dicussing this. If when I go to uni I encounter such stupid people who are talking such *****, then i won't be able to cope.
Lets think about it for one second shall we children, tell me two things. 1. Where is your digestive system in relation to your body, as you all don't seem to know. Then once you've figured out the answer to question one you should be able to work it out. Since the digestive system is no lower than you hips, your upper body is in the same position sat down as it would be when your standing, the only thing I can think of is that you think your digestive system is in your legs. Your digestive system pushes the food along so it probabaly wouldn't matter if you were eating up side down.
The only thing I have read so far on the benefit of sitting down over standing is that if you continously eat sat down you get into the habit of feeling that that is the place where you should only eat and therefore are less likely to snack, but I only looked at a few sources.
I will now make a heart felt plea, please think before posting just threads or at least do some research.