On what legal grounds?
Maybe in a totalitarian communist regime bitcoin can be made illegal, but in the free world a legal case would need to be made. I have never heard one, have you?
You don't need to live in a totalitarian and communist regime to experience banning of something. In EU for example, laws have been voted to ban glyphosate (Monsanto Roundup) use for example. In some countries of the free world some gov's plan to make the use of a bicycle with helmet illegal so why not BTC ? If a government judges it as a tool for money laundering they can decide to vote a law to make its use illegal.
I believe "lentzaj" has no room to speak on such matters because his account is stolen. I am unclear why you would acquire my account, but my name is aaron james lentz (lentz)(A)aron(J)ames. I have been dormant since July, when my email was breached. Also missing .20BTC from my kraken account. The .20BTC is gone, I understand. I would hope an opinionated individual, as yourself, would appreciate true ownership and not theft. I believe candidates, like yourself, give crypto a bad name. You should steal Terabox's, or better yet, Mt.Gox account instead.