Agreed. The relatively clear terms of the GPL have been very hard to enforce. Do you really think someone intent on doing evil will be stopped by a couple of lines of text in the header of the source code? Who has ever been okay with ethnic cleansing and torture but draws the line at copyright infringement?
Not to mention how reasonable people can disagree on where to draw the line. If you think the Israeli government violates human rights, does that justify banning all Israelis from using the software? What about Intel with its major facility in Kiryat Gat? Should you then ban the software from being run on any Intel processors, whether or not they were made in Israel?
I sympathize with the movement to hold coders and users accountable, but I just don't think this is workable.