If said people kept their opinions to themselves, the issue would never arise in the first place. Pretty much the whole problem in semi-public spaces like this is that folks with strong reactionary beliefs don’t tend to leave them at the door
`s/reactionary//` and you'd be right in your second sentence. It doesn't matter if it's action or reaction, people with strong beliefs, strongly held tend to be holding them because of some core set of ethical or moral principles and those things eventually are revealed in the day-to-day work.
As to your first - if people with a strong set of ethical and moral principles "just shut up" about what they considered ethical and moral essentials ... then they wouldn't be who they are. The only people who don't show what they hold good are people who don't hold as good much of anything.
Now if we're just talking "opinions" here (about things that are not ethical and moral, merely matters of taste), then yes, a person with "strong beliefs strongly held as a universal principle" is someone who is just an ass. But if I know someone is a raving Detroit Lions fan "on the internet", what kind of a person am I if I can't work with them?
Except people have enforced CoC's against people for expressing views on other platforms because those views make other people feel unsafe in those collaborative spaces.
I have only ever seen CoC's abused to push out people with anti-social just views.