The point of ARC is essentially an "IQ Test" for AI systems. It is meant to cover abstract reasoning capabilities of generally-intelligent systems like LLMs. What the author did here was build a system that only solves ARC problems.

The other tension is the fact that this score is on the public eval set. In machine learning, you typically have 3 datasets: training, evaluation, and test. The training set is the dataset that's used to update the weights according to your loss function, you are "encoding" the patterns from the training set directly into your model. The eval set is what you use to track performance while training, it is NOT used to update model weights, but shows how well the model generalizes. The test set is a private holdout set that is only used when you're "done" developing your model. The difference between test and eval is information leakage: you can use performance against the eval set to modify your hyperparameters and model architecture to get better eval scores. So while the eval set doesn't directly update the weights, it can indirectly cause "overfitting" by tailoring your model to do well on the eval set. What you really want to see is the private test set performance, not the eval set. For all we know, this model could be ridiculously overfit on the eval set and perform poorly on the private test set.