He proved that it is truly anonymous, in that he agrees that transactions are both cryptographically untraceable and unlinkable. He thinks that our decision to use i2p as a low-latency mixnet to disguise traffic is no going to prevent a determined attacker with lots of resources from ascertaining whether an individual (as in an IP address) is using Monero, but on that point we disagree. That notwithstanding, he does not fault the cryptography or the implementation behind Monero's transactional and address privacy.