Keep in mind that, much like Glenn Erickson [DVD Savant], Gary has never disclosed whether or not or how his equipment is calibrated. His reviews do provide some good information, but only some, and his captures are notoriously suspect in terms of colour grading.
It may have been harvested at 4K, but as RAH frequently says, a 4K harvest finished at 2K makes sense. You harvest at 4K to get all available resolution from the element and then master at 2K. It’s like when companies harvest large format at 6 or 8K and finish at 4K. There’s no 4K master here.
There are similar comments about Criterion's Nightmare Alley [1947] being from 2K instead of a 4K master and suggestions about Disney possibly withholding a 4K master from Criterion in the Nightmare Alley [2021] thread, which begs the question, "Why does everyone think 4K will automatically make...