I think you misinterpreted their comment. It's not that only people who use Unicode characters should be doing crypto math. It's that if you're doing crypto math, you certainly know what the symbols mean since they're used in the original specification, so reading the code shouldn't be a problem.
Yeah, so they don't actively handle them as greek letters and translate the variable name. Nevertheless, if you don't know what those mean, there is a great chance that you do not understand the whole thing enough, that way you shouldn't touch any crypto code.
following the old adage: "never roll your own crypto"
I am not saying you should use Unicode symbols in your code... What I am saying is that not knowing how to read greek alphabet, a corner stone of math and physics, does not bode well for someone working on cryptography algorithms, arguably one of the most practical uses of math.
