Just count, not limit.

Just comment out lines 28-31 of js/limiter.js

i.e.
https://gist.github.com/nciske/c92bcb12776db225255f

It’ll still show a limit (e.g. a suggested length) but allow the user to enter any length text (and show the count).

You could use some CSS to hide the progress bar output and total to just show the counter.