I've been playing Nautilus as my main support for the last few years. I don't think he's "too strong" since he does have his counters as everyone else. In fact, he shares a counter with Thresh and Blitz: he can't hook through minions. Blitz is overrated, to be honest. Everything he does needs to be within melee range, outside of his rocket grab. If you avoid the grab, then Blitzcrank is pretty much useless during laning. At least Thresh and Nautilus have other things in their respective kits that make them more valuable than Blitz in the bot lane.
Nautilus does have a lot of cc, and even his passive is enough to deter opponents from getting close. However, he plays best like a meat shield. In that regard, Nautilus is similar to Leona, by getting in the way of the enemies' path as they aim for the ADC, using his abilities to slow or neutralize those threats. This does bring significant risk to himself, because his shield is his only form of direct damage mitigation this early in the game. Sure, he'll last longer than the ADC, but it's nothing to compare to Braum's Unbreakable ability.
In short, yeah, I think Nautilus is "healthy" as a tanky bot lane support. I certainly didn't think he needed that slight buff to his Rip Tide ability in Patch 5.5, since his autoattacks do well enough without needing to rely on his abilities.