The Minutemen intended to build Israeli-style fence on that particular ranch, but after intense public pressure from the liberals, the landowners changed their minds and only wanted barbed wire.
It's their land, they can have whatever kind of fence they want, short of the federal government coming in and doing their job properly on that portion of the border.
Simcox could have said forget about it and saved the money for more elaborate fencing on other property. But he didn't. He helped them build the fence they wanted.
Let's not forget, it took 2 months to build a 2.2 mile long barbed wire fence.