Using Frost Queen's shouldn't interrupt channels

I was playing Katarina yesterday (like I do every day) and since I was with my premade I asked if they would let me try something new, and so i tried frost queens katarina. Yes I know it sucks on Kat and yes I know its garbage and I'm never building it again on Katarina, but I was mid ult and wanted to slow the enemy and it stopped my ult? I thought this was pretty weird imo, I know not many champs will abuse this but should frost queens be able to interrupt channels? Best example I can think of is champions like Xerath who this would benefit.