Its annual poa that they're trying to cultivate. It produces seedheads, unlike Oakmont.
My understanding is that Poa annua evolves and adapts to the low mowing environment of a golf green, into a grass surface with an increasing percentage of perennial plants with fewer seedheads. The reason Oakmont's greens are so tightly packed and seed free is a matter of time evolving into this surface. There's a USGA paper on this:
http://usgatero.msu.edu/v03/n09.pdfPoa transition at Chambers Bay, as well as Old Macdonald, is inevitable. Keeping Poa annua from dominating greens has been successful zero times west of the Cascades in the Pacific Northwest. It will take time. The first few years the greens will have lots of flowers and be soft and bumpy, but they will get better. Within a decade they will be pretty good, in 20 years they will be very good.
Our greens at Pumpkin Ridge have gone through a full transition (about 27 years old), and are better and faster than they ever were as delicate PennCross bentgrass greens fighting nature. The current superintendent appears to use a seedhead suppressor, and perhaps a growth regulator, but the greens are incredibly tight knit and smooth. Green speeds are regularly 10.5 - 11 feet, and can be rolled as needed for faster speeds if desired. Our course has pretty gentle slopes on the greens, and faster greens are required to make the short-siding penalty significant.
With that said, I like to play Old Macdonald when I visit Bandon, because I love those fescue greens, and know it's just a metter of time before they succumb to nature.