Doesn’t matter if their Epic servers are up to date if the attacker got a domain admin account somewhere else and can just log in normally to run the ransomware.
But also what are we doing running life-critical software on Microsoft-made OS? This is idiotic, it is great for gaming and excel but not hospitals. Microsoft could make another OS based on Linux or BSD and it could not be hot garbage. But that would eat into profits and take...effort. Linux and ChromeOS + 2FA is much better although not perfect.