While there has been a lot of progress made in the area of gay rights, not enough has been done to stop the hatred or discriminatory laws that are still on the books. Some people seem to think being gay is an illness, so gay people should be able to call in as a form of protest.
Not that it's a disease, but if it were, that wouldn't mean you could call in gay to work. You also can't call in myopic, for example. Being gay, if it were a disease, would still not impair one's ability to work, so calling in gay is a bad protest.
In late October of 1979, the National Board declassified homosexuality as a disease, making Sweden the first European country to do so.
Needless to say, not all countries have caught up. It wasn’t until 2014 that a World Health Organization panel concluded that there is no scientific basis for mental disorders specific to gay people, and the American Psychiatric Association’s treatment of transgender people remains controversial.
Homosexuality is different from sickness. One's sexual preference won't effect a person's performance. There are plenty of studies that say this and a company cannot let someone go because of their sexual preference. It is against the law to do so. It would probably not even work in some countries because many people don't know about this in the first place. They will think it is some kind of joke.
No, calling in gay, like the Swedes did in 1979, is not a clever protest. Being gay isn't a sickness, it is a part of life. One cannot just call in gay, like they can call in sick or they have an emergency. In fact, calling in gay is really offensive.