Why can't Aurelion Sol instantly reactivate Q?

It just dosen't make sense to me, because it makes it almost impossible to stun anytime past 6 or any assassin for that matter because they tend to be put behind or inside of you and occasionally right in front of you... but due to the reactivate delay you cannot stun then unless they walk into it, so I don't know maybe change it for the quality of life for Aurelion players. :)