Security issues are treated very seriously and will, by default, takes precedence over other considerations including usability, performance, etc... Best effort will be used to mitigate side effects of a security change, but PowerShell must be secure by default.

If you believe that there is a security vulnerability in PowerShell, it must be reported to secure@microsoft.com to allow for Coordinated Vulnerability Disclosure. Only file an issue, if secure@microsoft.com has confirmed filing an issue is appropriate.