This is Econ 101 (incentives matter). If you do not penalize negative behavior, there is no reason for it not to continue.
Those security vulnerability notifications should've gone into a tool to be actioned by a team (JIRA, PagerDuty, whatever) with follow up and verification (audit logs from their CICD pipeline confirming a patched version had been deployed to all environments dev through prod); that's an organizational and leadership failure, which should have consequences.
Disclaimer: I work in the financial services industry in security, but not CRAs.
EDIT: Agree with your assessment edit, its a total failure of risk management within the org. Again, you need dire consequences when that occurs.
EDIT: hoping to do this quickly to avoid comment/edit race conditions, but I wish I knew the right answer in re. penalties. Think about the system that exists with doctors, malpractice insurance industry, medical liability, review boards and the benefits society gets from transparent disclosure from reviews of medical errors. Honestly, short of jailing people, it's hard to see how criminal liability in this case could be worse than potential civil liability.
edit: also, so this is topical, the CEO is clearly incorrect. Even if one employee were somehow responsible for the unpatched version of struts being present on a particular system, there is guilt by omission/neglect for at least 1) poor secure enclave design (attackers getting access to the system, degree of access that system had, lack of partitioning of sensitive data) 2) lack/deficiency of red team/pen testing 3) lack of process in static scanning of deployed code.. it goes on. As someone noted, seems like negligent process given the degree they were a target. Granted, I'm going off the publicly disclosed information, so who knows..