Just curious - if they had stated they were homosexual, do you think HGTV could have fired them without facing lawsuits? Why should this be different?
If a new contributor on the 700 Club stated he thought Christians were demonic and were damning America, would that new contributor keep his job? Probably not.
HGTV has a large gay audience. They made a business decision. Any business is free to fire any employee at any time for any reason.