Useful would've been to send all non-citizen Muslim immigrants back to their homelands for good.
Something good did come of this. Every Obama-inspired peaceful protest ended up with obscene (maybe CIA inspired) chaos and the downfall of governments, with chaos following. In the US, those "peaceful protests" in Ferguson and elsewhere involved law breaking, looting, not being arrested. In Paris, from what we've seen, it was a peaceful protest. Why would Obama be in sync with a protest that didn't involve taking down governments, looting, and ignoring the enforcement of laws?
Besides he finally saved taxpayers some money.