Don't the Xenos have connections to one of the drydocks in liberty by the lore? Couldn't they use those contacts to get the ship produced in small numbers? Have them classify the ship as a shuttle while it's being constructed, but have it set up for the Xeno's to do some easy swaps, with schematics from the drydock, and turn it into a fairly effective bomber? Then thier contact just purchases it, "Form my dear old aunty." and sells it to the Xenos. Doesn't seem a stretch to me.