Is Ryze's interaction with his E and Muramana intended?

It's stated to be a 'single target chain area of effect' ability, meaning the first target will recieve spellvamp and Rylai's slow fully, while the targets E spreads out to get traditional aoe interactions (weaker slow and 1/3'd applied spellvamp).

If it is intended, can Sona's Q be changed to be similar in how it interacts with certain items? Right now her Q does not apply Rylais and Spellvamp fully, though it's not an 'aoe' ability per say. Since it's stated to be a 'point blank, auto-targeted' ability, can it be changed to apply the full slow?

While Ryze's says 'single target', it effects multiple targets, yet can apply effects fully to the first.