Issues In The Star Beast

Poul Anderson's "The Star Beast" convinces me that, even if humanity builds a peaceful civilization on Earth or in the Solar System, it should retain some means of defense against interstellar invasion.

Such invasion does seem extremely unlikely:

do other civilizations even exist?;
if they do, surely a civilization with an advanced technology will either overcome any warmongering tendencies that it may have or, alternatively, will have destroyed itself long before it has got anywhere near to attacking anyone else?;
surely anyone capable of interstellar travel already possesses far more wealth then they can possibly hope to gain by crossing an interstellar distance and attacking someone else?

However, if interstellar travel is possible, then some human beings might colonize extra-solar planets and one of those colonies could be irrational enough to attack the home planet, which is what happens in this story. Even if we need not fear extraterrestrials, and we do not know that for sure, we might still need to fear each other - although I also remain convinced that the production and distribution of abundance will make theft and war obsolete.

But that leads to another issue which Anderson addresses here and in later works and to which I will return in a further post.