The code in question is dual licensed: you can use it either under the BSD license or the GPL. It's your choice. In this case the person chose the GPL (and not BSD).
Perhaps now the "BSD is the only free license!!!" zealots will admit that they too want to restrict what others can do with their code. (There is no "100% freedom".)
The lesson from all this is: do NOT pick a license based on politics, religion, and fashion. Read the license (or talk to a copyright lawyer) and pick the license that works the way you want it to -- not because RMS or Theo or Joe Blow says it is the only true and FREE!!! license.
I'll start off with I think your assessment of copyright law may be incorrect but IANAL. I don't even play one on Slashdot so I'm going to skip over that part of your argument and look at the social/political issues. Ultimately I think that most things open source come down to social issues anyway. Everyone wants their credit.
Ultimately most of these BSD vs Linus and BSD license vs GPL licenses all seem to feel like religious debates so forgive me is I use a few religious analogies.
It seems to me the problem here is that the GPL and the BSD licenses are incompatible for some uses. So the a Linux developer convinced an OpenBSD developer to dual license his code. So far so good. The code is licensed BSD for ultimate freedom of use and GPL to allow its inclusion in the Linux kernel where it has to be GPLed. Then the Linux developer decides that his religion is correct and decides to quit giving any credit back to the original developer by removing the original copyright and license. That seems difficult to defend legally but let's assume that the BSD licenses actually allows this. (If so I'm sure Microsoft is pissed right about now that they included the BSD license in their products for all those years.) So what we come down to is a social issue. The original BSD developer has had his credit removed (something even nasty old Microsoft didn't do) so that someone in the GPL world wouldn't have to look at that ungodly BSD licenses. There isn't a practical reason for removing the BSD licenses so it has to be a social/political move.
What's the outcome of all this?
OpenBSD/Linux relations are strained a little further. With de Raadt and RMS in these camps that's probably inevitable anyway. Strong personalities create strong enemies.
I would guess getting BSD licensed software dual licensed just got harder since that seems to be the logic used to allowing this to be relicensed exclusively under the GPL. That's bad for everyone. Of course the retaliation will be a lack of code going back the other direction but I seem to get the feeling that getting a GPL developer to license under dual with BSD was probably already mode difficult than getting a BSD developer to license under dual with GPL. It's a big loss all the way around. About the only people who win are the proprietary software developers. At least in the Microsoft case they never seemed to have an issue with giving credit to BSD when it was required. Rejoice Microsoft wins again.