Stop right there at “Either abiogenesis is extremely rare...” I think we have considerable evidence that biogenesis is rare—our failure to detect any other life in the universe so far. I think we have no evidence at all that biogenesis is not rare. (Anthropic argument.)
Stop again at “I don’t think we need to take any steps to stop it from doing so in the future”. That’s not what this post is about. It’s about taking steps to prevent people from deliberately constructing it.
Anders Sandberg used evaporative cooling in the 1990s to explain why the descendants of the Vikings in Sweden today are so nice. In that case the “extremists” are leaving rather than staying.