It seems sensible to me.
It would work like this: Congress would bestow the status of federal civil unions on same-sex marriages and civil unions granted at the state level, thereby conferring upon them most or all of the federal benefits and rights of marriage. But there would be a condition: Washington would recognize only those unions licensed in states with robust religious-conscience exceptions, which provide that religious organizations need not recognize same-sex unions against their will. The federal government would also enact religious-conscience protections of its own. All of these changes would be enacted in the same bill.