Uh, there's nothing in your link about a government ordering Google to block Twitter? Since you say this is a common occurence, I'm guessing it'll be easy for you to find a source that actually supports your claim.
I think the main point is that it's trivial for people to circumvent the DNS level block by simply finding new DNS servers (in this case something other than local ISPs, Google, CF etc... still many out there) by asking others or simple googling here and there, and in extreme cases, at a physical level as in the article.
