If I ran a company and had LGBTQ employees, I would not want what you just described because it would be creating a hostile environment for those employees.
Coming into your workplace and telling your co-workers that they don't deserve equal rights under the law is just a shitty thing to do. It's an issue of basic respect and has nothing to do with politics.
You can attempt to frame it however you would like but what you want is an environment where people can only discuss political views that you agree with.
There is no harassment when someone simply states "I don't think same sex marriage should be legal.". And before I get downvoted into oblivion, I don't agree with that statement, I'm actually completely apathetic to it and think it's unimportant.
Politics is more or less the mechanism by which society takes collective action. Since people are broadly speaking in favor of free value, pretty much every policy that has nearly exclusively positive or at worst neutral effects has been implemented. It's not like anyone would oppose such policy! So "politics" exists as the realm of policy proposals that help some people and harm other people. All political opinions involve harming someone. If they didn't then they wouldn't be "political" opinions, they would just be opinions.
If I ran a company and had LGBTQ employees, I would not want what you just described because it would be creating a hostile environment for those employees.
Coming into your workplace and telling your co-workers that they don't deserve equal rights under the law is just a shitty thing to do. It's an issue of basic respect and has nothing to do with politics.