Annoying Zz'Rot strategy and suggestion on how to fix

Hello, I have recently played two games where the enemy top laner was a Zilean.

Sounds bizarre enough as is, but all they did was rush Zz'Rot Portal and put it on their tower very early on in the game. They threw their bombs on the Zz'Rot minions and just sat back in lane. This prevented our top laner from pushing and forced our top tower to fall way earlier than it should have.

Now, I'm not crying OP OP nerf, as of the two games, I won one of them, so it isn't an unbeatable game breaking strategy. It is however, a very annoying and, in my opinion, a very unhealthy way to play the game.

I feel Zz'Rot portal should be used in one of two ways:

1. An aggressive structure to push down a lane, putting it into a lane late game and putting pressure on that lane until someone is forced to deal with it.
2. A defensive structure to protect your base, when you're behind and need some counter pressure going.

However, this early game rush of the item turns it into both. A defensive structure and aggressive structure that both protects the owner's tower and attacks the enemy tower. It creates this awful situation where the tower protects the Zz'Rot, and the Zz'Rot protects the tower.

When I was laning against the Zilean, and he put his Zz'Rot under tower, I had no way to go and destroy it, since my minions were always forced back by the Zz'Rot, and if I were to try and face tank the tower to try and destroy the portal, the Zilean would just kill me.

So my suggestion to fix this is Zz'Rot portals must be placed outside the range of an alive tower. So Zilean tops can rush this item still, but at least there would be some counterplay. They can put it behind their tower's range and be out of reach of the enemy top laner, and force the top lane to either deal with the Zz'Rot or try and walk behind the tower to deal with it.

The two ways I mentioned would practically be unaffected. I feel as though the core use of the item will remain the same, as an aggressive or defensive item.

Thoughts? Is this too hard of a nerf(I really don't think it is, but I could be wrong)? Should the range be buffed slightly if this nerf were to take place?