How many de-anonymization schemes have withstood more than casual attacks? There's so much stock data available that I wouldn't want to bet against someone using historical data to de-anonymize a stock and then place a bet using insider information. The use of ML would even give plausible deniability – just imagine a prosecutor thinking about the odds of successfully arguing that your model couldn't have produced that result?
I'm almost positive it's not using homomorphic encryption (at least in any real sense). It's misleading how they seem to suggest that they are, though.