Is it possible to have the plugin lock the start/stop engine? 

Currently players who are not authorized on the code lock and unable to access the fuel and resources can still stop the quarry.

yes i have the same problem some toxic gamers turn off other game quarries and it's not nice

+1 on this :o)

Since last Rust Oxide update it became doable

QLock Hype ... :o)

I created this function, works for me!
this will only aceppt the start and stop from who where on the whitelist from codelock.

void OnQuarryToggled(MiningQuarry quarry, BasePlayer player)
		{
			var codelock = quarry.GetComponentInChildren<CodeLock>();
            if (codelock == null)
            {
                return;
            }
			if(!codelock.whitelistPlayers.Contains(player.userID))
			{
				// Puts($"{player.displayName} has toggled a quarry");
				if(quarry.IsEngineOn())
				{
					quarry.EngineSwitch(false);					
				}
				else
				{
					quarry.EngineSwitch(true);					
				}
			}
		}