RE: Why didn't these guys develop LakBuzzard, buddy, you seem to be asking so many questions that are answered as far back as the last few posts!
Ivanhoe brings a mass amount of exposure, experience, credibility, profile etc.
Had Derek tried to go it alone, the capex would likely have choked us via explosive dilution, and not to mention, even with the dilution, it still would have taken longer to extract the same amount of oil. Whenever your thinking about a project with cashflows it's paramount to consider the Net Present Value of the project. Because Ivanhoe will generate bigger/faster cashflows, Derek's call it 40% stake could well have a larger NPV than had they gone it alone.
Not to mention, from a risk analysis point of view, bringing Ivanhoe on board as a partner significantly improves the risk/reward profile.
I'd say they picked the #1 choice for a partner considering the project.