The antihack doesn't "stop" hacking 100%, but hacking while the antihack is installed let's others know about it on the /status page. And then its up to them to decide whether to play you or not.
If someone doesn't have Antihack installed, it's up to you whether you want to risk playing them or not, you can try telling them to install the antihack too with the latest version of war2combat.
Even dellam uses the antihack, the status page just shows him as "Unknown" all the time. I've seen another player named dabu- appear as Unknown a few times too.