Their data had a 50/50 split between criminals and non-criminals, so an 89.5% success rate is actually pretty good. You're right that this algorithm wouldn't be

Their data had a 50/50 split between criminals and non-criminals, so an 89.5% success rate is actually pretty good. You're right that this algorithm wouldn't be practical to detect criminals in the general population (ethical issues notwithstanding), but I don't think they're suggesting that. They're just offering a neat statistical explanation for a 2011 study that showed that under certain controlled conditions, people are surprisingly good at spotting convicts.