Cynically perhaps I'd imagine that increasing number of tor users for his node would be a great benefit if he wanted to reduce the possibility that his own traffic could be easily tracked. If you're the only user of a Tor node I'd imagine it's far easier to track traffic and potentially deanonymise if not decrypt some communications.
This was my first thought as well. And specifically if anything he was doing got flagged the crypto party would be an excellent cover for why he was using Tor and TrueCrypt to send things to random people
