I like how it portrays magic in Gensokyo as being science and sufficiently advanced technology, but the scarlet sisters are still immortal winged rapscallions.
Guess the flying-controlled-by-limb-position thing would explain why Rumia just sticks her arms out parallel to the ground when flying, what with the alternative being the human pretzel technique.
Plus, I guess that'd make Mystia an Iron Maiden, hyuk hyuk hyuk.