Now your old account is being used for scams. Privacy is a double edged sword. So also is the concept of freezing accounts. If you want that, you have banks. I created a website for people to sell files for steem dollars. www.steemfiles.com.
The biggest security flaw in Steemit are the users. If they limit Steemit to veteran bitcoin users, then this would not happen. But that is not what Steemit is for.