I read this as the manager being lazy because they were giving in to the unwritten pressure from their manager to force attrition (less work) rather than trying to help their team members by protecting them (more work).
If the manager is "giving in to unwritten pressure" -- particularly when it comes to making decisions that they, on some level, know intuitively to be wrong; and which more to the point, harm not only other people's careers and health, but the company's reputation and prospects for long-term success --
Then by definition, it is the directives of senior management that are at fault.