They precisely say they use it as a better alternative to bash. Obviously they don't think that Python is a better alternative here... or did I misunderstand the question?

Not obvious to me that they think Python is worse than Perl, and make the phrase even less sensible.

Weird wording yes. I read it as "yes perl is better than bash" (I assume for tasks that need actual programming languages), "no it's not worse than python".

I'm not reading it as "it's not worse than python", I am reading it as "the choice was between bash and perl, python was not an option for reasons unrelated to its merits"

So you genuinely believe that they think Python is a better choice in this case, but still chose to go for Perl because they believe it's worse? How does that work?

It works by not mixing two different people: the commenter and the implementer.

Also, it works trivially even in the case of the implementer - he might believe Python is better, but chose Perl because he likes it more

The same reason people write C++ instead of better^TM alternatives.

Pick the tool you already know and focus on solving the problem.