Two more posts from Schiffman in Sukenik:
Here is part of the first:
Continuing to see the cave as a genizah, he repented his view that the cave had been entered already in antiquity. In this way he explained some sherds that appeared to be dated later than the period of the scrolls.
Regarding this “genizah,” he had concluded that the scrolls had been placed there, as unfit books (ספרים פסולים), as in the case of the Cairo Genizah. He based his view on the terrible conditions of the Hodayot scroll, with its disconnected sheets. One scroll was only broken fragments and he assumed that this was the condition in which the scrolls were brought to the cave in antiquity.
He noted that other scholars disagreed with this conclusion, seeing the texts as hidden in a time of religious or political persecution. Kohle had suggested that these scrolls were put into genizah after the fixing of the biblical text, as they were no longer to be used.