As some siblings have commented, it's probably the failure to get back and document it. But the desire for job protection is not uncommon. I saw it when I worked on testing satellite power converters at a large aerospace company. There were procedures and paperwork for everything, but the test procedure for one series of power converters did not work. Only one technician knew how to actually test them. He led me through it, and he had plenty of time to update the procedures, but refused to do it. It was gross and obvious what he was doing, but somehow he was allowed to get away with it. There was no union.