Personally, I think it will be cool to kayak underneath the rags; it isn't everyday that we get to boat through the middle of something so unique.
I get the whole "clean is relative" thing, but seriously, take a look at that section of river...it's full of concrete and rebar - and, like it's been said, it's already a done deal. Let's make the best of it; let's pray for high water and boat the crap out of it while it lasts. Who knows, maybe some of Christo's concrete blocks will fall in and make some new play waves.
"Always look on the bright side of life whistle whistle whistle..."