I have a few problems with this point of view. For one, these closures are frequently temporary in name only. Here's a link to a notice of extension of a "temporary" closure in the
Angeles National Forest. This closure has been in effect since 2005, supposedly to protect "critical" yellow legged frog habitat. It represents the total closure of 1000 acres, about 1.6 square miles. There is no human access allowed in this area. So, point one, temporary isn't always what it appears.
My second problem is that I don't see any effort to analyze the issue from a balanced perspective. I understand that we may at times want to take actions to protect certain species. But, where is the tradeoff against the value of allowing humans to continue to access one of the prime hiking areas in the San Gabriel mountains? Does that have no value? Where is the tradeoff that shows that a total closure is the right action, as opposed to simply limiting access to existing trails? How do we trade that off against the value of protecting a species that has no known value save for it's mere existence?
Species become extinct every day. They will continue to do so with or without our efforts to control that process, and in fact if all humans vanished from the Earth tomorrow species would continue to become extinct.
As I mentioned earlier in this thread, I believe the Endangered Species Act and many other environmental laws have become tools to accomplish other objectives. Science is not perfect. Statistics can be mistaken, misunderstood, and yes, even manipulated to create a desired outcome. If you can manage to have a court declare the yellow legged frog endangered, you can close an area altogether. That this area was known to be a place where certain Forest users complained about the nuisance created by rock climbers on Williamson Rock may or may not be a coincidence.