No humans go, no information returns.

Sending an acorn-sized probe to another galaxy to make more acorn-sized probes: what even is the point of that? To make very slow grey goo a reality?

If actual humans find a way to go to Andromeda (other than waiting for it to arrive, heh) and want to, good for them. Otherwise we should actively discourage anything like the project proposed

This is a study of the feasibility of launching an intergalactic colonization wave (and its implications re: the Fermi paradox), not a proposal that humans should do that (it would be just slightly ahead of its time for that!), or a discussion of the ethics or higher-level utility of doing so. It would be refreshing to see someone discuss the things paper actually discusses. To use early-2000s terminology, the paper's future shock level is higher than that of most HN readers, leading to rather banal discourse.

In any case, I'm fairly sure the authors agree that sending mindless automata to colonize the universe doesn't seem like a great idea. Nevertheless some alien intelligence (including an Earth-based AGI) might find it a completely reasonable, even imperative, goal.

But sentient machines or uploads (assuming for the sake of this this thought experiment that they are possible)? That's a different thing.