Ah, ok.
Yeah, well perhaps the whole "headlock" thing is a way to get around it as mentioned.
Also, just to clarify, Defensive Mode doesn't make you invisible. You can still see people on your radar that are in this mode but they simply appear as a faded blue dot rather than a distinct, blue one. It's easy enough to see them IME / IMO although some say they have trouble with it. Either way, not a bad deal if your intention is to avoid randoms.
I rarely have problems with griefers myself but a lot of that is simply due to avoiding those I feel will likely cause problems. .....I know you know the drill already. You can usually tell just by observing them but then again, there are situations where these folks learn to exploit like hanging out in areas where it kicks people out after missions, etc. .....but again, I just don't feed into all that and it's usually a non-issue after a brief hassle.
The tools work but they can also be exploited to an extent. The good news is that Defensive Mode is there if you find folks getting more annoying and it does help in that regard IMO / IME.