Should Nautilus' passive stun?

Recently I saw a post by Meddler mentioning that struggling tanks (Nautilus was mentioned as a maybe) may get some buffs in patch 5.5 or 5.6. In my opinion, Nautilus could really use a buff that helps him carry his team late game. As it is he lacks damage and the ability to mitigate damage for his team even when he is doing well. His lockdown is amazing, but it does not prevent champions with ranged abilities and attacks from shredding his team. As such now is probably a good time for this discussion.

I personally prefer the idea of improving on Nautilus' strengths instead of his weaker points when buffing him. Thus, instead of improving his damage output or early game tankiness directly, I think making his passive's CC stronger is the way to go. It would reinforce his identity as a tanky late game CC machine, and help him generate more threat through his CC.

Examples of ways to change the passive: Replace the root with a stun of the same duration starting from level 1. Replace the root with a stun of the same duration starting from level 11. Apply a stun of half the duration of the root concurrently with the root starting from level 11.

For those unfamiliar with Nautilus, his passive is currently: basic attacks deal an additional 2 + (6 × Nautilus' level) physical damage and root his target for 0.5 (1) / 0.75 (6) / 1 (11) / 1.25 (16) / 1.5 (18) seconds. The numbers in parenthesis are levels at which the root durations come into effect. This passive can not trigger on the same target more than once every 9 (1) / 8 (6) / 7 (11) / 6 (16) seconds.

Right now Nautilus is fine when his team is even or ahead in the mid and late game. Getting caught by Nautilus in such cases usually leads to a rapid demise, and a stun instead of a root from his passive may not make him too strong. However, if his team is doing poorly he has problems staying relevant even if he is doing relatively well. This is because he does not do enough damage to carry, and does not do a good job of preventing ranged enemies from dealing damage to his team. He can peel melee champions well, but rooted enemies still deal damage. Giving him a stun on his passive may make him impactful enough to help carry the game even when his team is behind. The idea here is that if his passive stuns he will be more of a threat to the enemies' DPS because he can interrupt it. That will effectively let Nautilus boost his team's durability so long as he can successfully attack the enemy carries.

Of course there will be some other consequences to changing his passive, some of which may be desirable, others not. If Nautilus can stun monsters early game with his passive, his early clears will be a little faster and safer because his shield will stay up a little longer. He will also be a little harder to duel, especially later in the game. Most consequences will likely come down to Nautilus effectively being a bit tankier, and thus doing more damage as a result of his shield staying up longer. In game testing would be needed to sort all the consequences out. I really like Nautilus, but I do not want to give him a free win just for getting to the late game.

What would suggestions do you have? What do you think is the best way to go about buffing Nautilus, or should he even be buffed?