Rakan and new Zeke's

My first thought when seeing the changes were "Which support champions just want to ult and dive in the enemy", to which Rakan was an obvious answer. It would also finally give him a reason to stick around fights with his pathetic AA range.

I'm seeing a problem though : Since he can't AA while ulting, he can't actually proc the 40% slow part of the item. I'm just wondering if this is an intended consequence or not, aka if Riot personally believes it would be too strong or is looking to wait and see.