If your security relies on hidden information then it’s at risk of being broken at any time by someone who will find the information in some way. Open source security is so much stronger because it works independently of system knowledge. See all the open source cryptography that secures the web for example.
Open source poc and fix increases awareness of issues and helps everyone to make progress. You will also get much more eyes to verify your analysis and fix, as well as people checking if there could other consequences in other systems. Some security specialists are probably going to create techniques to detect this kind of sophisticated attack in the future.
This doesn’t happen with closed source.
If some system company/administrator is too lazy to update, the fault is on them, not on the person who made all the information available for your to understand and fix the issue.