No one said anything about code “needing” to be open source.
The issue here is that code became public the moment it was uploaded to a public repository. Just because your organization has reckless hiring practices and fails to secure its proprietary code shouldn’t entitle you to be able to use the legal system to doxx every IP who viewed it on a public website in an attempt to track them down seize their machines and claw back the code. How would you feel if I posted a snippet of the leaked code here in this comment and then tomorrow you receive a legal summons or your house gets raided in an attempt to make sure you don’t have a copy?