I think honestly flight should be something you should have to trust someone to let them cast on you. Here's why, and alert me if I'm wrong:

Lets say I enter a champion's stand and I'm not flying, I'm about to fight an invoker and I can deal with his quicksand (wimpy 0, champs stand to prevent getting lagged out, and he's not likely to land curse on me or I'm low weight enough to flee out of sand and I know this).

If he has the insight to cast flight on me and then buffet me, it knocks me out of champs stand. An invoker/arcane combo could most easily abuse this just by casting flight then buffetting, then following and neuro disrupting. In essence, it removes half the point of champs stand if its useless against invokers who have things like flight staves or a healer or whatever.