Is “Why every researcher should sign up for their ORCID ID” Grammatically Incorrect?

Is “Why every researcher should sign up for their ORCID ID” Grammatically Incorrect?
Brian Kelly, UK Web Focus, January 31, 2013

The use of the singular with a universal quantifier is problematic in a world with two genders. the use of either gender alone has political implications, the use of both (a la "his/her") is awkward, and the use of the plural is grammatically wrong. There's where the options end for most people. But there is a way out: drop the universal generalization, and use your noun to indicate scope. Instead of saying "Every researcher should use their..." say instead "Researchers should use their..." Of course, you may think you've lost your punch. But now that you've changed your noun,  world of possibilities opens up, as in "All researchers should use their..." or "Mindful researchers should use their..." or even "Gender-neutral researchers should use their..." In general, when you want to make a point that applies to more than one researcher (or anything else), don't use the singular form of the noun. More...