If your team can't write a few hundred lines of critical section code in another language, or at least pick it up in a week - especially when the syntaxes are very similar (this isn't going from closure to java here) - you have bigger issues with your team than their language choice.
Yep, no single language except C(/C++) is enough by itself (potential exception here is Java, but even there it's still useful).
C has become the lingua franca of computing. You can call everything (except Go) from C and you can call C from everything. So you want to actually reuse standard libraries, you will want to know C. And if you're a good C hacker you'll know C++. I'm not saying you'll necessarily use it, but you'll know it.
The vast majority of python programmers do not know how to call C/C++ code and are therefore limited to pure python libraries exclusively. They usually use writing to files and os.system() as an alternative. Needless to say, the performance of this approach can be questioned.
