Premise Problem With District 9

In retrospect, the most basic premise of District 9 falls flat with an audible thud.

Quasi-governmental corporate thugs will do anything for the big bucks.  They want extraterrestrial weapon technology to sell to the highest bidder.  Billions and billions of dollars. They want it so bad that the Big Boss will sacrifice his son-in-law to get it, breaking his daughter's heart, even to the point of having him vivisected to death.

That's pretty greedy, if you ask me.

So how do they try to get these extraterrestrials to cooperate?  They put them in shacks in a concentration camp.  The aliens are reduced to the criminal mindset that we are told must inevitably come to those who live in shacks.  They become greedy opportunists themselves, who will do almost anything for .. cat food.  It seems that a local native crime lord (and why did the evil corporation let him into the District 9 camp?) has a larger collection of alien technology than the evil corporate thugs, because he knows a secret that hasn't occurred to the corporate thugs: bribe them with the thing everybody knows they like: cat food!!!! 

These aliens may be refugees, but they are not sheepherders (or zeepherders or whatever) from planet X.  Many of them are engineers with knowledge of the very technology the baddies want.  Christopher Johnson (the alien who is a quasi-protagonist in the film) never is conflicted about turning over his alien technology, because he is never offered anything for it.

What corporation wouldn't wine and dine our extraterrestrial guests (even if keeping them prisoner, prisoners can still be treated like guests) for such a huge pay off?  What government wouldn't do that, for that matter?