In the stealth mode knife he is talking about, NO, I don't see a problem with it. "not a admin though" I have used this tactic several times before and as previously stated, this happened only a dozen times "Since source release"
I understand keeping this rule, and I am in favor of it, but as with all "issues" on the server- it's open to interpretation by most people. Like everything else, there is a "Tactic" in almost every situation. The knife in front of a enemy while ammo is available is nonsense of course. He isn't talking about that though. I have knifed in order to make sure the other team doesn't hear firing of my loud AK/M4, hoping that they didn't see on radar it was a knife. I say yes to the stated situation, no to knifing in general.
my 2 pennies!
Case in point. A couple days ago I had a teammate behind me holding a choke point. Somehow, the T got behind us. Instead of taking us both out from behind he thought it "stealthy" to come in and knife my teammate from behind. I knew instantly what was going on and turn around and shot him in the head. Had he been using "team" skills he would have just taken us both out with his AK. Instead his greed of a knife kill sacrificed his teams probable win. And now I think enough admins have weighed in here pretty much all on the same page I doubt there should much room for error on this subject when it comes to those who frequent this forum.
If you want to knife buy MW2 and go commando on everyone, CSS's Mechanics makes the knife in the game pretty much useless trying to use it 9 times out of 10 will just get you killed and hurt your team.