Oxide recently added an OnQuarryToggled method. It's not perfect, but this patch does a sphere check to ensure someone who is authorized is close to the quarry and if not turns the quarry back on:

        void OnQuarryToggled(MiningQuarry quarry)
        {
            if (quarry.IsEngineOn())
                return;

            var codelock = quarry.GetComponentInChildren<CodeLock>();
            if (codelock == null)
                return;

            var owner = covalence.Players.FindPlayerById(quarry.OwnerID.ToString())?.Name ?? "unknown";
            var position = quarry.ServerPosition;
            BaseEntity[] results = new BaseEntity[25];
            var by = BaseEntity.Query.Server.GetInSphere(position, 0.75f, results,
                entity =>
            {
                BasePlayer player = entity as BasePlayer;
                return player != null;
            });

            var near = "";
            var i = 0;
            var whitelisted = false;

            while (results[i] != null)
            {
                var player = (BasePlayer)results[i++];
                near += (" " + player.displayName);
                if (codelock.whitelistPlayers.Contains(player.userID))
                {
                    whitelisted = true;
                }
                
            } 

            Puts("Quarry owned by " + owner + " at " + position + " turned off. Whitelisted player nearby? " + whitelisted + ". Nearby players:" + near);

            if (!whitelisted)
            {
                quarry.EngineSwitch(true);
            }

        }

You can submit a patch on plugin page

Orange

You can submit a patch on plugin page

Only existing developers can access that.

Someone on my server had a good idea. I could just create a standalone mod to stop people from turning off the quarry and then apply for dev with that plugin. It would also let me add a configurable chat announcer and possibly play with some electrical damage (also optional).