I don't mean to offend but this is ridiculous and I say this as a woman. Just leave the damn seat the way you used it, if it's inconsiderate for you not to leave it lowered for me, it's inconsiderate of me not to leave it up for you. Turns out able adults are perfectly capable of operating a toilet.
I always got the impression that this is a predominantly US cultural thing to fret about. I mean, women have the lift the seat as well when the toilet brush has to come into action.
Because you are moving a not completely dry object to and from a porcelain bowl with the express intent of brushing away faecal matter. Chances of dripping something (water probably, filth possibly) on the seat are non-negligible.
