Yeah, because the probability that a random alien would recognize "humans would rather not be reassembled into somebody else's compute substrate" as ethically relevant is slim.
Hybrid Theory: Reconnaissance nanobots are dispatched to the planet which is to be disassembled, soaking up every piece of data imaginable. The planet is then converted into computronium, which as a background thread, runs one or more simulations of that planet's hypothetical future, in order to extract any possible scientific value from the developments of the native species, or just as a simple curiosity.
If this is true, we were likely destroyed a long time ago, and we now live in one of those simulations. Any cosmic activity outside of our solar system is a mere fuzzy approximation, and even if we develop interstellar travel technology, we'll hit some sort of "Truman Show" wall if we try to leave our imaginary sandbox.
Makes you curious to keep watching the Voyager probes, does it not? :)
