Admittedly, it’s a hypothetical.
I also recognize you rightly caveated with the word “respectable”.
So, given that, can you imagine Apple or Google or Mozilla actually firing an employee who, using their name, criticized Christians who were against gay “marriage”?
I wouldn't know about this one way or another, but I can absolutely see these companies taking a hard line against employees who publish anything like this even when the employees take positions that the company's leadership fully supports.
The dilemma a company faces is that if they allow Employee X to freely publish opinions like that, they have compromised their ability to discipline Employee Y for publishing a different opinion in a similar case.
This is why most companies don't like to get involved openly in politics on controversial matters. There's very little upside in alienating a large portion of your potential customer (and employee) base.