take over?

http://www.news.com.au/business/companies/bhp-billiton-on-outback-buying-spree-in-south-australia/story-fnda1bsz-1226422062223

Surely there is a good chance BHP will pony up some money to get a crack at TRF's "Alladin's cave" of "potential Olympic Dam" size deposits.

At the dirt cheap price of TRF at the moment why wouldn't BHP just take the whole thing over?

More to the point, what is it about TRF (and its holdings/tenements etc) that mean BHP has not taken it over?

Just posing questions as one who had some TRF in the past but is firmly out of the market (except super) until after the US elections.