They're just embassies.
Perhaps the non-aggression treaty should include fixing borders, so that both sides promise not to colonize systems colonized by the other, unless they already have colonies in that system, which would go a long ways towards alleviating the problem methinks. That, and if the AIs paid a bit more attention to the possibility that a threat to obliterate them is very, very real... if it's clear that a player's fleets are vastly superior and ready to attack, that should weigh in on things a bit.
At least it ain't SMAC diplomacy. SMAC factions habitually asked for bribes in order to sign treaties, even when they were down to their Last base. The response, naturally, was always genocide...
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-- The thing that goes bump in the night