Sure, the point is this: Yellowstone is an island, genetically. If we don't do something to increase the genetic vaibility of those bison inside of Yellowstone, which are widely regarded as the most genetically pure bison left, then some group will ultimately petition the USFWS to list the bison as endangered, forcing the fed to either preclude, or list under the endangered species act.
If listed, then a whole new set of problems arise, as we see with the wolf. Under a listing, the needs of all other species become much more subservient to the one. In this case, we'll see federal mandates to conserve bison as wildlife in areas where the states would have less say in where. That truly does mean impacts to livestock producers in so much as the historic habitat went as far as Pennsylvania. Once it gets in to that realm (the fed), groups like Center for Biological Diversity and others have a much better chance of working the system and getting bison across a broader swath of land than what is currently being considered. The decision to list will come down to the genetics. While there are numerous commercial bison herds, most of those are intermingled with cattle genetics at some level.
Maintaining genetically pure strains of bison through state conservation is the best way to eliminate the argument that bison will become extinct. It's the best way to keep the management in states hands.
SS - The Henry herd has about 500 bison in it. Right now, they share ground with livestock (there are two allotments, I believe). Some people are saying that the bison are impeding on the livestock producers forage (on public land), and so some folks are buying them off. For the most part, those bison don't hurt other wildlife species in the henry's and there is no major fencing that occurs other than maintaining the usual 4-5 strand barbed wire on allotments as far as I know.
That's really what folks are looking at, small, isolated herds where the geography and land uses are compatible with reintroducing bison. The Henry's is a fine example to base some reintroductions on, but really, I'm not sure we'd want to go down the road of buying off grazing permittees to allow a few hundred head of bison to roam in isolated tracts.
I'm not familiar with the problems that the Book Cliffs herd is causing.