Correct - their current v4 chip covers ~602K SNPs and they have > 1 M customers, so you couldn't uniquely identify all of them by genotype. But given the frequency of rare variation in humans, you'd expect to be able to reduce a given genotype to a much smaller set of customers.
It only takes about 20 snps to uniquely identify someone. They genotype to the order of hundreds of thousands of them. As far as identification (and the risks of misidentification) go, it's pretty much just as bad as sequencing.
