Grounding Totem Does not Work on Quell?

I just realized a massive bug. Why is it that grounding totem can eat any spell but does not work against an Evoker’s Quell? Blizzard needs to fix this ASAP…its ridiculous.

it’s a physical ability (the dragon roars at you), so it’s another ranged physical interrupt like counter shot

Where does it say physical ability in the spell?

Quell; spell=351338

School Physical

Wowhead has a clean entry of it from the spell database. You can’t ground physical abilities. It’d be like grounding a kick from a rogue.

Why would a spell caster have a physical interrupt…