And wearing a collar is not performkng anything kinky.
I see nothing explicit in that necklace.
Maybe to you it does have some additional meanings, hell maybe it does to her as well, but so do wedding rings, and I’m going to go out on a limb and say you aren’t critiquing people for having profile pics with those.
I guess people with this knowledge are probably part of that subculture, not sure why would they be pothered by that fact. For others, like me it looks like random necklet.
You may not think it's appropriate for a workplace, but their employer clearly does or they wouldn't be employed.
Why does it matter that it has a significance beyond "it's pretty"? As long as it's not obviously discriminatory in nature (like a necklace full of swastikas), then why does it have to pass your "decency" tests?