Top lane naut is viable because, in addition to cc, he has sufficient base damages and waveclear.
Obviously, if you nerf his base damages and waveclear, he can lane as well, but it will hurt his jungle even more, since jungle Naut needs those AoEs and base damages.
Note that almost all of his abilities are some form of AoE as well, so the nerfs are even worse for jungle naut with the mini monsters in the jungle.
Raptors, for instance. A 10 damage nerf would technically nerf 70 damage from the raptor camp, 10 from each raptor. While in -lane you have at least minions to deal dmg to other minions, in the jungle, you have to do all the damage, so he has to finish the mini-raptors off one-by-one (or burn W, and, as mentioned in the post, he has mana issues, so that sucks) more often.
Basically, you cannot nerf top naut without nerfing jungle naut. It is not as clear cut as Top lane Tank ekko vs AP ekko. It's closer to shoving Lulu from solo lane to support, but still slightly different.
How could you nerf top naut without gimping jgl naut? There isn't any way to do it.