Freeze of the account happens on BP level. That is, there is a command that makes eosio software reject any transactions from that account, but since there are 21 producing BPs that requires running on all of them with an updated list.
But for exchanges to selfcensor, at the start they just needed to send those tx back to that account to block it. Now that there are tools that allow you to create new accounts the situation becomes harder, but the blockchain is transparent so it is doable.
I'd think it is something that is more important than discussing the dress code for the participation in the conference calls.
RE: "The Dog Ate My Blacklist!"