Even bubblesort would return in the time it would take to send the array to be sorted to the GPU
GPUs can be used for training but there is no requirement for the model to be executed on GPU. For example, a network can simply be created for incrementing a counter which could be what a "choose the best sort" network ends up doing.
I guess someone will just have to try this.
It begins with quicksort, it switches to heapsort when the recursion depth exceeds a level based on (the logarithm of) the number of elements being sorted and it switches to insertion sort when the number of elements is below some threshold.
I think machines can do this too.