Good. Dragon is extremely powerful right now. Especially that first buff it gives. Being able to take it so early shouldn't be a thing.
Assuming 100 AD, you get 8 AD out of it, which is less than a long sword.
Otherwise, the solution to early dragons being strong is not to completely gut one of the best early dragon getters, making them have a hard time even getting dragon normally.
Isn't Dragon supposed to be taken on as a team of at least 2-3 people pre-20min? Sneaking in and taking the thing solo is fine. What isn't fine is a powerful buff such as a Tier 1 Dragon being obtained at ~3 minutes by 1 champ. Pantheon by himself shouldn't be able to get it that early. That's the point.
Early dragons aren't a new thing you know. Fiddlesticks, anyone with spirit stone + feral, and several others were known for their early dragons.
Otherwise, the buff ISN'T that powerful early. Having an extra 5+ AD in lane is not going to make a difference often. Even if it did, the solution would NOT be going "hey there's this one visible early dragon getter, let's completely remove his shield vs dragon and severely nerf his attack speed".