I don't personally like this.
The server's not meant to be someones personal bubble in which you operate only within your own group.
For what it's worth, you can make chat size and font size smaller, as well as show less lines, then edit the screenshots you take and add new custom chat lines instead of showing the ingame chat

Main chat should always be visible to everyone as people might ask questions (even to you, over main chat). This is especially true in the case of administrative messages, since we really prefer not using /say to appear red text, but instead we just use main chat to handle most of the rulebreaks.
Censoring players, but not admins from main chat wouldn't do pretty much anything to help you achieve what you described in the opening post, as admins are quite loud in the server with our banter and bickering
