BUG ANALYSIS: What it means to be isolated? (Kha'Zix)

Currently, when an enemy has no targetable allies within a certain range, they become isolated for Kha'Zix's passive. At least that is what the wiki states, and that is what SHOULD happen. Yuumi negates isolation while attached to an ally, even though she is not targetable, this directly contradicts the description for Kha's isolation, I believe that she should not remove isolation, however if this is intended, then Riot should update the tooltip/description of his passive, what is strange is I remember similar cases functioning as expected, such as Fizz not counting when untargetable, correct me if I am wrong, but if this is true, why is Yuumi an exception? I think Riot should think hard about what should remove isolation, while clearly stating why it is the way it is in his tooltips, in a way that is fair and not too overly detrimental to Kha'Zix or his enemies.