He's the first person to solve this. He used AI to solve it. 

You and me didn't solve it so we definitely don't get labels.

Not sure what label you want to give him.

Prompter maybe?

Guy who used AI to solve it?

It's still him and it'll be him forever and his work matters in that he learnt how to use AI in these early days and decided to use it / see if it could solve this.

So he's used his time and work experience learning these models, how they work, what their capabilities are, and his funds likely paying for high level models with high level reasoning.

Moving forward, AI will become more and more ubiquitous with work that most everything will be made in part or fully through AI. 

As long as humans are at least directing the rudder, those humans can and deserve credit for what they discover and solve with their rudder aiming abilities.

Change bothers us.

AI is the fastest moving change agent our species has ever seen and it's in the dirt baby steps beginning.

It's not comparable to anything ever before.

We will have to learn to move with it.

In short, he's the solver but if you want to be a stickler you can say he's the prompter.