Its going to be used like that. I am warning you all
Actually, If I remember the original post cleary (lazy to get back and read me - don't judge me), it lifts the user one and a half block high, so with collision being in 1.9 you would hardly burn anyone. While the user can ascend higher, which enforces your said problem again, I think that can be solved by not giving it fire damage and/or lift the player more higher as they are floating above the targets head in a few seconds, to keep the flames from burning their head off. It should still deal damage (half an heart), since you're streaming
fire, but with my though put into consideration, it prevents well enough for the firebenders to not use this power in means of offense, because fire ski is meant to be a mobile thing.