"AI can be thought of as a search problem over an effectively infinite, high-dimensional landscape of possible programs. Nature solved this search problem by brute force, effectively performing a huge computation involving trillions of evolving agents of varying information processing capability in a complex environment (the Earth). It took billions of years to go from the first tiny DNA replicators to Homo Sapiens. ... we have little idea of how to find the tiny subset of all possible programs running on this hardware that would exhibit intelligent behavior."
That's... a bizarre argument. You might as well argue that since heavier-than-air-flight is a search problem over an effectively infinite, high-dimensional landscape of possible machines - and that since it took evolution billions of years to produce birds, we have little chance of stumbling upon a working design for a wing.
Of course evolution's 'brute force' breadth-first hillclimb takes billions of years to find solutions to problems. It's undirected and unintelligent. Engineers don't have to perform undirected unintelligent searches across the infinite space of possible solutions to problems, they can think and plan and learn. I see no reason to see AI as a particularly different class of scientific endeavor, more complex than rocket science or nuclear engineering or biochemistry, such that ordinary, unenhanced human brains can't hope to comprehend it sufficiently to design machines that are capable of intelligence. This sounds a little like an 'if man were meant to fly, god would've given us wings' argument.