>>64509917
>Because any alien species that had the mindset and culture to be capable of forming such an alliance in the first place isn't going to suddenly decide that they need to turn into the Imperium and kill everyone they meet.
But how do you know that? They live under the same competitive pressures as we do.

>Your logic is self-defeating. If alliances with new people are inherently bad, then by that same logic the alliance you ALREADY HAVE was bad to create as well.
Our alliances were NOT created with new people. That is the failure point of your logic.
Our alliances were made with people we've known for centuries and millennia. We originally DID TRY to kill them. A dozen times over, in many wars and attempts at conquest.
Hell, plenty of peoples were wiped out because of just that. Human history is full of genocides where entire peoples of strangers were wiped out, or if they were lucky, enslaved. The surviving peoples are the ones who killed the other ones. We are the descendants of those who killed the losers.

>You're shooting yourself in the foot, not for any pragmatic reason, but to force an ideology which is ill-suited for survival.
It is entirely pragmatic to not risk extinction under the vague assumption that a competitive alien species (they have to be competitive or else they wouldn't have survived this far) would not see us as a risk the same way we see them.
Our planets are very easy to destroy and ruin for human habitation. All it takes is one space rock and Earth is no longer capable of sustaining advanced life.
Why take the chance?

>>64509931
>You assume belligerence as a default response to newcomers
No. I assume it to be uncertain, and not worth the risk to make assumptions either way because our entire species is at risk.
It's safer to just wipe them out than assume they're friendly for some nonsensical reason.
If they made it as far as we did, they're as big of a bastard species as we are.