That's great, but once you factor in all the people who downloaded this plugin and are otherwise slightly harder to fingerprint, it's still 99% accurate!
I was saying the number of people who install a plugin that varies the user agent is tiny, and even then there are other ways to detect (just check out the lists of things, screen sizes etc.)
And the big picture is, regardless of these small imperfections, a digital fingerprint is over 95% accurate! So that's very valuable!