They are playing whack a mole with a thousand holes.
And to the government, this is a non-problem. They can get more budget money to buy more mallets and hire more mallet wielders, and it's job security for life. It's a war that under the existing paradigm will never be won.
limitations of form concentrates the minds and enhances the power and effect of content.
And it will continue to, if Twitter sticks to the philosophy of its current experimental interface. 140 characters will still be shown in the feed, with a link to view the extended tweet. Don't feel like writing more than 140 characters? Then don't! I'm sure Twitter will include some kind of 'legacy' config option where it will artificially disallow you from writing more than 140 characters if you enable the setting.
Old programmers never die, they just hit account block limit.