Can it be, "the Klingon does not work"? If so, would an English translation of "the Klingon is not working" (more natural sounding) be correct? Or would that require some progressive verb form in the Klingonese?
I typed "Klingons are not going to do any work," and it said that "Klingons" was a typo and should have been "Klingon". I see that both are in use for the plural, but there's no report option for typos-that-aren't, as we know :(
Paging through the Google results I see 131 for "the Klingon are" and 170 for "the Klingons are". If you eliminate Google's weird inclusion of the greengrocer's apostrophes, it would look like "Klingons are" is only about a 2:1 favorite on the web. I suppose people think of it like "the French." Google NGrams do tell a different story: http://bit.ly/2INR9wI.
I'd never noticed the plural "Klingon" before, but you're right, it's everywhere. I wonder how much weight this quotation, published in the Washington Post, is placing on that scale:
"The Klingon are a very, very direct culture -- not subtle at all," says Marc Okrand, a student of their civilization who converted their society's attributes into words, phrases and idioms when he developed the Klingon language."
I don't remember hearing Marc use "Klingon" that way. We'll have to ask him.
Hyraxes have the same problem, though the results for “hyraxes are” vs “hyrax are” is about 5:1. The Google ngram graph backs up the case for “hyrax” as plural being rather old-fashioned.