The developers of SciPy are maintaining a codebase that is 18% fortran, according to [1]. The only language that makes up a larger part of the codebase is python.
Don't you think it's possible their opinion on fortran is actually informed by quite a bit of experience?
"Citing packages in the SciPy ecosystem" lists the existing citations for SciPy, NumPy, scikits, and other -Py things: https://www.scipy.org/citing.html ( source: https://github.com/scipy/scipy.org/blob/master/www/citing.rs... )
A better way to cite requisite software might involve referencing a https://schema.org/SoftwareApplication record in JSON-LD, RDFa, or Microdata; for example: https://news.ycombinator.com/item?id=24489651
But there's as of yet no way to publish JSON-LD, RDFa, or Microdata Linked Data from LaTeX with Computer Modern.
You'd be surprised; About 25% of SciPy (much of the numerical computing portions) are in FORTRAN. It turns out that decades of compiler/numerical computing research has made the FORTRAN compiler generate numerical code which runs faster than GCC/Clang today.