The argument is that we're istinctually biased when assessing whether an entity is what we consider intelligent/living, or not.
It'd be simpler in the post to contrast, say, an "electronic" alien driven by AI, versus a syntethic machine, made by humans, with the same (hypothetical) AI; we'd istinctually recognize the former as intelligent/living, but not the latter.
The post is essentially retelling the carbon chauvinism concept.
"What if we encountered an extraterrestrial life form which had independently developed anthropomorphic tendencies" is a totally different question from "What should we think when we encounter a heavily engineered system designed by humans to be anthropomorphic?"
If a human-looking alien came out of a UFO, it would shake my worldview even if I realized it was made of tissue closer to plastic than human tissue. I don't feel the same way when I encounter a doll in the toy store.