There is an airstrip at Yalgoo that Oxiana had refurbed so they...

There is an airstrip at Yalgoo that Oxiana had refurbed so they had a place to land when they were refurbing their own airstrip at Golden Grove (and as a community gesture, of course).
The Gero strip is for the commercials like Qantas (Airlink) or skywest - Yalgoo is too small for them, not enough people to make it worth flying to.

They could've chartered a flight to Yalgoo from Gero once they came in, but then again, they may have been doing the sell on the roadtrip in (2 hours) from Gero.