Oh yeah, there is precident. I've heard that Shakespeare once used they in the singular, but I haven't found that instance yet. These inconsistent instances might be errors or signs of a usage psssing in and out of favor regularly. There's no clear way of knowing. It's still not grammatically correct by any organized standard though to use a singular they -- at least not yet. Expect judgement (both spoken and unexpressed judgement) by readers whenever you make the choice to use a singular they.
Thanks for the link to the article though, it was fun.
P.S. The whole language could use a huge overhaul.
@nostalgicroxas There were a few attempts during the 1990s to create new words that fill this gap in the language. Personally, I favored tey, tem, & teir as singular versions of they, them, and their. All of these invented words went over like lead balloons in a china shop.