Not to mention that the article attacks the currently known technology with reasonable extensions, and treats those as a Ark or cruise ship that somehow has to get to another solar system. Rightfully skeptical there.

But there's so many other ways, ways that our descendents will think of that were beyond our imagination. Think tiny robots and gene bombs, or peppering interstellar visitors with inert payloads, etc. Once you abandon the meme of a brave ship full of sailors, it's fair to return to an optimistic future millennium where humans are sending life to the stars.

And that's completely without considering all the very real possibilities in our solar system, which are more challenges of degree, rather than kind. Perhaps human lifespan in orbit is 30 years at first. It wouldn't be the first time a population took root in a hostile area.