We're far enough away from any likely candidate systems that we would only pick up very high power omni-directional signals - in other words, intentional beacons. Such a beacon is unlikely to be highly encoded (though there might be an associated signal that *is* highly encoded, and to which there is a pointer in the beacon signal). In other words, we don't have to worry too much about the Kolmogorov complexity of extra-terrestrial signals, because we won't be "overhearing" anything.