What is the nature of your outrage exactly? Bash is very difficult as a language to write code in. JS is very familiar to a lot of developers and its syntax is orders of magnitude easier to understand than Bash.
The prejudice against JS developers is that they are seen as low class janitorial code monkeys by ‘real programmers’. It hurts these people even more because the language just succeeds and succeeds despite all the hate.
I would say that it's more that Bash is good at something and JavaScript is good at other things and just because they are technically scripting languages doesn't mean that they are naturally a good fit in each other's domains. The README's comment tends to point towards an idea that all languages that can write scripts are equally interchangeable and of all choices JavaScript is the perfect choice. To people that are working on a variety of scripts in numerous languages who all have individual advantages and disadvantages, it comes off as nonsense.
I think definitely there are better alternatives to JS in command line world like python but if someone decided to use something other than bash as a programming language that’s a win in my book. It has its place for basic scripts and general command line trickery but anything beyond that is using a hammer to do brain surgery.
I do think JS would be much better than python. It's more to do with familiarity.