Those consequences shouldn't include "losing your job" or "being treated differently at work", else there's no freedom of speech.
How would LGBT community liked it they could lose their jobs for being LGBT?
Under the interpretations until recently of federal statutes [1], and under the law of most US states, they can, and largely the same groups fighting against marriage equality have been fighting to preserve and extend that condition, as well.
[1] Though recent EEOC decisions finding that discrimination based on gender identity and/or sex stereotypes are subtypes of discrimination based on sex may significantly limit the degree to which that is in practice true under federal law, but AFAIK those agency interpretations have not yet been tested in the courts.
The fact that LGBT people can be fired without recourse is a central issue.
What if a gay principal is fired for supporting gay marriage. What if someone is a religious pacifist and the ballot issue had to do with gun control? Are those just opinions or is there no other option for a person given his or her identity?
I'd even go so far as to say that sometimes opinions are core to someone's identity. As in, the person would be fundamentally different if that opinion changed.
I'm not sure the issue is so cut-and-dry as you presume.
Yes, they can. Freedom of speech is a right that you have before the state, not in front of you fellowship.
Everyone is fully entitled to refuse to follow you, on whichever ground they please, including a public or private statement by you.
Please don't assume that I am speaking about that.