Phones are not a pub-sub system like Twitter is. Once you block someone, there is no way they can contact you directly. You have to go and read their Tweets in some manner to see what they are saying.

Stephanie Guthrie was appears to have been literally trying to sue this guy because he called her mean names (for which she blocked him), and was using a hashtag that she liked to search on. Apparently, Tweets from people you have blocked are still visible if they are using a hashtag that you search on. This could possibly be a technical limitation – it's not like Google gives you an option (apart from SafeSearch) to filter sites you may be offended by. Come to think of it, this is literally like trying to sue someone for putting up a site indexed by Google that may come up for search terms you use.

So I would say the case for being similar to repeated phone calls is invalid.