That was never the definition, it still isn't. You can't marry your daddy, for example, as much as I'm sure you want to.
Believing that the historic definition of it should remain the same is not bigoted given that gay couples have an equivalent option. Or of they don't then fine, change that so they are equivalent.
And I don't really see why anyone should be compelled to make a product promoting a message which goes against their conscience.
The mistake they did make though was initially accepting the order.