Even if he can't freeze it, he has access to the public ledger and with some effort can figure out who sent money to whom. Either of those two parties could the

Even if he can't freeze it, he has access to the public ledger and with some effort can figure out who sent money to whom. Either of those two parties could then get a visit and politely invited to reveal the other. If you want (more?) anonymous you need Monero or Zerocoin.