Being against the war but for the troops is hard to maintain at times (tip to Instapundit).
While these people really are the fringe in my opinion (though with a good third of the opposition party hoping our surge in Iraq fails (and even 11% of Republicans), it is sometimes tough to believe), their actions resonate somewhat with a lot of mainstream opponents of the war. These repulsive actions make the mainstream uneasy but do not rouse indignation as they do for war supporters.
So I highlight these actions by the fringe not to tar the entire anti-war side (even those who are really just anti-Bush) but to remind the mainstream that you can go too far in opposing the war.
I may find it silly to say you support the troops but oppose their mission, but if believing you can do that means that the member of our military won't be treated as our Vietnam veterans were treated back home, then I'm all for the anti-war side expressing and acting on that belief. If we insist on all or nothing support, we'll get nothing from those people.
These "peace" protesters oppose America but try to pull the Americans who are surely not anti-American but are anti-war (or even anti-Bush) into their orbit. Highlighting the actions of the lunatics on parade should have more of an impact on the more reasonable anti-war side than the pro-war side.
We can all be equally disgusted, but it is way more important for the anti-war side to see the lunatics and be revolted by their behavior.