I'm not sure what's going on in that series of articles. On one hand, it's saying wyoming sheriffs have power over federal agents, OTOH, another article says that there was a settlement (not judgement), and that not allowing feds to enter a county to do their business was itself illegal. There seems to be some back and forth on this issue, and the articles are focused on the mid-90's.
So it LOOKS like that website is saying the courts uphold the power of the sheriff to allow or deny fed agents to operate in their counties, while it's also saying the courts have not ruled directly on the issue.
??