I bet the Telvanni LOVED that one! "Do you have any idea how hard it is to give Therana her food 3 times a day while climbing up a rickety old ladder up her fly wells, WHICH WERE MEANT TO BE *FLOWN* IN!?" LOL. i can see it now...
Aryon probably has a throw down rope ladder now.
I think it would be very difficult to enforce such a law on the Telvanni.
[Imperial Legionarre swims out to a secluded island and shouts up the verticle shaft to Divyath Fyr's chamber]
Legionarre: HEY, UP THERE! I HAVE COME TO DECLARE THAT THE EMPEROR HAS BANNED THE PRACTICE OF LEVITATION!
[Fyr slowly floats down, in his full Daedric armor, with bonemold-clad female warrior-clones of himself surrounding him, and glowing fingers surging with energy.]
Fyr: Excuse me?
Legionarre: Uh....never mind.