Not to beat the dead horse too much more, but that makes absolutely no sense. Weyland could not have been stupid enough to think that he only needed a crew barely capable of getting him to an alient planet, and that after that the crew was expendable and everything would go exactly as he wanted it to. The man hadn't a clue what he would find.
The whole crew wasn't expendable. Just Shaw, Holloway, Millburn and Fifield - aka the non-Company freelance associates who were kept out of the loop about the
real mission.

Like HAL 9000, David (the "top shelf talent" who he didn't even have to pay) was programmed to carry that out all on his own, and he succeeded.
"Barely capable of getting him to an alien planet?" Captain Janek and
his men (plus David) got the
Prometheus down on LV-223 just fine. Not a scratch. Weyland/Vickers didn't mess up there. Only mistake the female doc made was getting too close to a desperate Shaw (and it's hardly her fault David didn't sedate her strongly enough). And NO ONE saw the Zombie Fifield attack coming. (I counted three, maybe four killed in that fight - how well you think they'd have done against a full-fledged Xenomorph?)
With the exceptions of Millburn & Fifield, who had no clue what they were in for when they signed up, and loose-cannon Holloway (and let's face it, they're the only ones we're complaining about), the crew of the
Prometheus was "pretty damn good." Take those three (plus Shaw) out of the equation, and everything DID go exactly as Weyland wanted it to - right up to the second the Engineer ripped David's head off and caved Weyland's skull in.
True, Weyland didn't know what he'd find. But the man was
dying. He was
desperate. (And he certainly didn't consider himself an amateur.) The minute he woke up, the countdown clock started. He had days left, if that - he had nothing to lose. He could only bet everything on this one roll of the dice and hope for the best. If not - hell, he was dead either way.