There's no evidence they knew about the ship or the Alien before they got the signal.
Then why plant Ash on the ship? An Andriod that wouldn't be targeting to create more aliens. I mean, it could be lucky coincidence, and that's sort of how it struck me when I first watched the film. He's analyzing the thing, curious about it, because by default he's programmed to be, and the order that Ripley found out about was just a standard procedure thing, as harsh as it was.
But then why send an andriod on board a towing vessel for no good reason. Why not at least let the crew know about it?
It just doesn't add up very well in my mind.
And there's nothing to suggest that the company knew about the ship prior to Aliens. If they had, why wouldn't they go to it and figure out what was going on. It was Burk who sent the colonists out there, almost 60 years after Alien, only after learning about it from Ripley. Burk wanted the alien, not the company, at that time. It wasn't until Alien 3 that the company officially knew (or realized it wasn't a hoax) about it (excluding ACM as cannon), and they send a very Hazmat looking group to go get it.
It'd be more appropriate, if they knew about the alien, to send a specialized team in. If Aliens visited earth, I wouldn't want a stressed out trucker being the first guy he met...
Also, I'll point out, It was the Nostromo (Mother) than got the distress signal, not the company, at least that's not implied. And they were essentially lost in space, nowhere near the time that they were supposed to wake up from Cryo. Remember Ripley calling antartic control or whatever it was? If it was a serious issue, even after the alien appeared on board, why didn't they try to contact earth and get some advisement? I think it's because they don't have those communication methods at that point, or at least the ship isn't fitted with them. So they're acting alone, doing what they're doing because its in their contract. The order to retrieve specimen, Ash defending it, all of that seemed like a default way of doing things. 'Oh you found an creature from another world? bring it back, it's more important than you.' Thus, the lives of the crew being secondary. I can imagine why they'd do it that way too. Say it's a disease, and humans are now space-traveling, they happen across the disease, maybe it turns out it can affect humans. the company would have going to assume that if such is the case, there's no reason to assume that the crew can do anything about it anyway, so let them die. That way the company can learn from it, and figure out if it's present anywhere else.
Ash did refer to the Alien as the perfect organism. I don't think he meant compared to us or a lion, but against all organisms, even microbial ones. It's resilience, life cycle, acid for blood, it's a potential mass murdering machine. Virus's infect a host to recreate, the Alien does too, only it's not a single cell. That would be impressive to anyone. So think of the Alien as a Virus, the company would want a sample, so they can understand it, protect against, and potentially weaponize it.