While I don't know whether or not Feitan manufactures those keys, I believe the answer is that they don't. More importantly though, that article doesn't really provide any detail one way or the other. Advanced Protection works with any FIDO/U2F key. Feitan's keys are valid AP keys. Titan keys are valid AP keys. Yubico keys are valid AP keys.

That a key works with AP doesn't say anything about who made it, and that article just says that you can use Feitan's keys with advanced protection, not that they're Google's key manufacturer. In fact I think that article is from before Google announced the Titan keys, but I'm not 100% on that.