I agree that gay allies need to engage in direct action, because that's how civil rights get recognized in this country.
But there's just so much wrong with "calling in gay," particularly in light of the fact that some morons persist in calling homosexuality "a sickness." Why make the point for them?
In 30 states including Missouri and Kansas, a person can be fired for being gay, so encouraging this action could jeopardize people's jobs.
Many gay allies have no complaint against their colleagues and employers who have done as much as they can within the confines of the law. However, the brunt of this action primarily falls on one's employer and colleagues.
It utterly loses sight of the fact that the problem is with a government which has unconstitutionally established religiously motivated discrimination as law.
I'd rather see gay allies start paying their taxes "under protest," with a massive class-action suit claiming that gay people unfairly pay a disproportionate share of taxes, as they're categorically denied a constellation of favorable taxation benefits granted to married heterosexuals. That favorable tax treatment is intended to encourage wage-earners to provide for their loved ones.
A suit would force the government to explain its rationale why a certain classification of taxpayers (who engage in a lawful sexual practice) are undeserving of the same encouragement, when no other sexual practice (lawful or otherwise) functionally disqualifies anyone from realizing such preferential treatment.