I personally know the Archaeologist who had the last say in shutting down the Calico dig. He had no choice, his .gov employers forced him to. I have also personally handled what very well could be classified as primitive Acheulean and Levallois style finds from the ancient shore line around Lake Manix.
The official line at Calico was, Leakey's selections of natural vs artificial seemed to be irreproducible. Overall, Leakey's view that the Americas must have been occupied more than the then-dominant view was obviously correct. Before Clovis-first-and-only, the official line was that the Americas had been colonized a mere 3000 years ago, or perhaps 5000 years ago. Archaeology of the Americas needs a dental plan, it's like pullin' teeth...