it might be coded as a cone effect instead of a skill shot (since his anchor is quite large, it would just be a thin cone
if it is coded as a cone, it is a simple fix for riot provided you can prove this bug
cone effects (as far as I know due to an earlier bug in the game) hit targets that were in the cone before the half second delay on casting, so if it would have been impossible to dodge, but was dodged, it still takes effect
if this really is true, his hook could bring someone back from base or something after recalling XD
as others have pointed out to you, without a recording, it isn't proven technically