Did he pick Excalidraw as the project to work on, or did the audience?

It's easy to be conned if you're not looking for the sleight of hand. You need to start channelling your inner Randi whenever AI demos are done, there's a lot of money at stake and a lot of money to prep a polished show.

To be honest, even if the audience "picked" that project, it could have been a plant shouting out the project.

I'm not saying they prepped the answer, I'm saying they prepped picking a project it could definitely work on. An AI solvable problem.