If I miss the point, why would a security agent change his way of check people going from land to airside? It's exactly that point what makes it a secure area...btw, a knife is not a tool for any aircraft... Buy a different tool in your local diy without a knife and you will not have this hassle any more.
I stand by my previous point, the security agent cannot just believe you'll not pass on the knife to another person with other ideas than opening oil caps...
There's no reason to discuss it, they're not there to think, just execute their work.