If Lee' UIt didn't root in the animation, it would function the same Trist's ult
In the sense that even if you flash during the animation, it wouldn't change the direction of the skill and you just get shot back toward her team anyway.
This is what the Rioter meant by "wasting your flash"
The problem with these abilities is that they're archaic and the code is dated. My theory (and it's just a theory, maybe Riot can confirm) is that the trajectory is calculated at the time of the cast, instead of after the animation finishes. This is why even if you flash to the opposite side of Trist while she's already in the animation for her ult, you still get launched in the original direction.
This problem is archaic season 1 spaghetti code. It is also evident in champs like Ez. If you hit Ezreal with a bind, stun, root, etc after he starts the animation for his E, he still shifts to his original target, but arrives at his destination rooted.
The only way we're going to fix this is by updating some of the archaic code. Maybe have trajectory be calculated at the end of the animation as opposed to at the intial cast.
Maybe some Rioter could give us some clarification as to how these things are coded, because it seems to be more of a problem on older champion. There's also things like Casseo ult flashes that exist too
can do it too
in the argument like every champ, lane and role in the game wants to buy it... in that case why don't we just all play
so we can be immune to cc?