It shouldn't have to. He may not have the option to write Coffeescript at his job, or he simply may not want to (for any number of reasons.)
Even if Coffee isn't in use at the moment, if it provides some value it would be worth promoting within the organization. New technologies routinely pop up, and the onus of proving their worth ultimately lies on the developers, even if they aren't the decision makers when it comes to selecting which ones are adopted and which ones aren't.