We aren't, that turn of phrase is only being used to set up a joke about developers and about Unicode.
It's actually a pretty popular form these days:
a does something patently unreasonable, so you say "To be fair to a, b is also patently unreasonable thing under specific detail of the circumstances that is clearly not the only/primary reason a was unreasonable."
I think people are making explanations for it - because it's effectively a digital black box. So all we can do is try to explain what it's doing. Saying "be fair" is more colloquial expression in this sense. And the reason he's comparing it to developers and unicode is a funny aside about the state of things with unicode. And Besides that, LLMs only emit what they emit because it's trained on all those said people.
Why are we being "fair" to a machine? It's not a person.
We don't say, "Well, to be fair, most people I know couldn't hammer that nail with their hands, either."
An LLM is a machine, and a tool. Let's not make excuses for it.