Poppy's Ult Stops Leona's E Dash

I understand that the root will not trigger, but why is Leona's dash not triggered when she lands an E on an ulting Poppy? That is neither dmg nor CC on Poppy, it is an effect for Leona.

Is the ability supposed to read "It is as if all abilities targeting Poppy simply fail" rather than "Poppy is immune to all CC and damage"?