Stand up to wipe? Of course you stand up to wipe! What is the alternative? Stick your hand down the loo to get to your arse? Some people are wierd! You don't stand up with your buttocks clenched though: you have to perfect standing with your legs apart and your buttocks open otherwise there is indeed a danger ofspreading the poo.
You girls will enjoy the discussion I once heard about how the way you wipe your bottom defines your character. I don't recall the issue of whether you stand or not being discussed, but it certainly went into how many peices of paper you use at a time, and whether you fold it or scrunch it before use. I am a copious user of paper and like to scrunch it, in a half orderly/folded way. It still riles me to see my children take a strip of paper and then not fold it but dab one small part of the strip to their arses. That isn't wiping! Who taught them to do that?