Veigar event horizon

Veigar fairly recently had his event horizon altered, in that it showed where it was being cast. A needed change. However the issue I've encountered is champions are able to move through his stun once the walls are already up simply by using an ability to move rather than walk. Specifically I want to mention Yasuo. Which is not an uncommon opponent. Veigar casts Event horizon in lane, and yasuo simply uses sweeping blade to pass through the walls.

The wording of Event Horizon vs sweeping blade makes me believe that Event Horizon should take priority "stunning enemies who pass through the perimeter" where Yasuo's ability states "Dashes through a unit"

This is my first post, but this is something I thought made veigar not viable being a low mobility champion and event horizon being his only engage and escape ability