Although the Golan falls under Israeli law, residents of the region wishing to write "Israel" in the Hometown section of their profiles are not give the option.
For example, if someone from Qazrin fills in the Hometown space, the only option will be "Qazrin, Syria." The same is true for all of the other Jewish towns, including Ramat Magshimim, Geshur, Mevo Hanna, and Had Nes.
It is not for Facebook to decide the national origin of Golan residents. At the very least, Facebook must include the option of writing "Israel" in the hometown section, as it has done with Jewish residents of the West Bank.
Check out HonestReporting's new Facebook group, Facebook, Golan Residents Live in Israel, not Syria. As of this posting, it's rapidly grown to 646 members.