This answer was from an account that I unsubscribed from but wanted to answer it from my active account too!
Yes. By blocking a twitter use you are simply stopping them from following you and from your tweets showing in their timeline. The only way you can stop people viewing your tweets is to make your account a private account. By having a private account users have to request to follow you, this allows you to manage who can view your tweets, it also means other users can't retweet you.
