Extending that idea to code reuse in general, is using perl only "worth it" if you're "good enough" to debug flaws in that? What about an operating system? Or your computer's processor? Sure, all these things can and do contain bugs, but it's still very much "worth it" to use them.
Not always, it's not.
Diebold couldn't pitch a viable voting system based on Windows, because they couldn't prove all the failure modes.
Any decently reviewed code will have the same issues: as a minimum, you need to audit all the failure modes for the hardware, OS, and modules, and fix them or deem them acceptable: otherwise, you have code that you MUST not sign off on.
Advocating anything less is advocating lousy software engineering. An engineer MUST NOT sign off on sub-standard work, or he compromises his integrity, and the reputation of his entire profession. You can choose to accept or not accept a given piece component in your system, but only when what it does is well known, audited, and the risks of failure deemed acceptable.