We should be defining intelligence by outputs rather than the methodology by which they achieve them, or else the only acceptable definition for intelligence will become "a human brain".
If you choose the former, you can comfortably say airplanes don't fly, they just glide, if you want to define flight as flapping of wings. Yet airplane flight is more efficient than if we tried to achieve it the biological way.
Similarly, it seems apparent we'll be able to solve many tasks that we attribute to "intelligence" using methods different than the biological ones. We shouldn't limit ourselves to comparing the methodology when deciding if it has achieved the goal, it is more productive, from what I've seen, to define by output, and to increase specificity there if the result is still unsatisfying.