Annoying mechanics between Ahri's ultimate and Aurelion Sol's ultimate

Ok, first of all, hi.

I got one question: Is it on purpose that, when you ult with Sol an Ahri (while her standing really near to you) to knock her to the outer range of Sol and she uses her ultimate that moment, that she ignores the ultimates knockback effect?

To be honest I didn't test it so far in a botmatch or with a friend (I dont have any cry ) so I can't say how it looks like in the view of an Ahri! But it happened now quite often in ranking, that I try to get rid of an annoying Ahri by ulting her, but she just happily standing right beside me in the (at least!) one second she should be out of my personal space! Because... she ulted in the same moment. Looks a little weird in my opinion but I'm still not sure if Ahri just can do that. Ulting - while being knocked back. I'm quite sure there is a difference between the interaction of Ahri's ult while her being knocked back in other situations... for example while an Alistair headbutts her. Doesn't look the same as when a Sol pushes her.

Can someone have a look on it please? :) and tell me if this just should be that way, or is really some little, not really wanted interactions.

Thanks a lot! & Have a good day!