Doesn't make sense... This premise seems flawed by two aspects:
- The maintainers can introduce vulnerabilities unknowingly themselves
- They should only merge patches that they fully understand
It feels like they are not capable of detecting a vulnerability when they see one. meaning that they themselves can potentially introduce tons of new vulnerabilities unknowingly.
In this situation it would be for the best to have a large pool of contributors capable of detecting such issues, instead of closing it even further.