Oops, I should have been more clear. By "reactionless flight is trivial" I meant in general, not necessarily for persons playing Superman. Wingardium Leviosa is a spell that generates reactionless flight, and it's literally the first thing kids learn. It can be used on persons and has already been employed in combat in MoR (e.g. "Chaotic Twist!"). Then there's other things like Quick Quotes Quills that float and move reactionlessly as they write, brooms, flying carpets, etc.. Since Hermione is a stupendous genius with spells even in Canon, and MoR!Draco is no slouch himself, it just seems likely to me that they would have tried to come up with something. Leviosa on a chair, or Hermione's shoes as a semi-permanent enchantment ("Wait, Draco, I know some 3rd Level spells..."), or something like that.

But it's nothing the Rule of Cool and the MST3K Mantra can't fix. :)