<Snipped quote by Shorticus>
And what if someone stared at them like they were a piece of merchandise, clearly sizing up all their weaknesses and strengths as one would with a horse? Then asked for a gene sample and to see sketches of their entire biological systems?
Because that's how Xim greet everyone. Until you prove your intelligence, you aren't a person so much as just a wad of raw organic material, which should be refined and modified into a more perfect form.
The Xim have a lot of strengths- they're smarter, stronger, healthier, hardier, and faster than most others- but diplomacy is not one of them. 
As noted previously, a "peace or flight" response is pretty much standard procedure for the Namilee at this point.
If they did not feel immediately threatened by the Xim, they'd probably begin interacting by trying to decipher their language and establish an air of peace. They'd potentially engage in trade, though they may be curious - and cautious - about the Xim's desire to procure samples which would provide them with Namilee DNA. At the very least, they'd want to know the why behind this; but being trusting, there's a fair chance they'd concede, but might ask for similar samples from the Xim.
(After all, why let an awkward and potentially threatening negotiation get in the way of a good experiment?)
But they'd much rather trade information, such as cultural information and scientific learning, especially so they might get an understanding of the Xim's outlook on the galaxy and their technological advancement. Then they'd decide what technologies they're willing to reveal to the Xim, as they'd want to make certain they don't give a race technology too far beyond its present state as that might risk, y'know, more genocide. Again.
I'll talk more about this later. I have to finish an essay.
