Exactly. Armed guards are needed at protests precisely to protect peaceful protesters from being murdered by cops. Yes, it's obvious that you can't legally use weapons against officers. But every officer knows that the moment someone's life is threatened, the law doesn't matter for shit. If a cop is threatening to shoot me, I have no problem with shooting them right back. Maybe I'll go to jail, oh well, better that than being dead. Maybe the cops will still kill me. Oh well, at least I took a fascist with me.

Cops are able to act with such monstrous inhumanity precisely because there are no armed protesters to deter them. You don't see cops firing rubber bullets point blank unprovoked against armed protesters. Because those cops know that if they try that shit, there's a good chance they're not going home tonight. They can have the whole corrupt legal system behind them, but all none of that matters if you're lying dead on the ground. Every cop should have to attend every protest knowing that if they abuse their power and start actually threatening innocent lives, that they will be among the first dead if violence breaks out.

Cops are ultimately bullies. High school bullies grow up to be police officers. And like any bully, the only thing they understand and respect is force.