Yeah, but which scenario are we looking at here?
a) W-Y has had previous encounters with xenomorphs (or even manufactured them), and now they're trying to put the genie back into the bottle, or find their lost pets and bring them home.
b) W-Y has standing orders to look for *any* lifeforms in the universe, in addition to whatever other missions their ships and crews might be charged with. I would think that *everyone* involved in the early days of space exploration and colonization would consider a possible First Contact as Priority One.
And if it *is* Scenario A, then, again, why the hell send some working stiffs on a space tug? It would make a helluva lot more sense that if you needed someone to find some xenomorphs, it would be a Space Marine ship you'd want to send with guys armed to the teeth.