I think the important point about this is the difference between "Floating" and "Hovering" (Something i have seen on Enemies). I think the important difference here is that "Floating" only works for movement itself, not for beeing stationary. I support this claim with the character animations that show the character standing on the ground while beeing stationary and not flapping the wings on the spot to stay above the surface, while hovering always shows the character/enemy beeing above the surface.
You may be correct that is is working as intended. However, my argument is that this is BULLSHIT, and that it SHOULD render you immune to surfaces.
