Now a days almost every country believes that to express personal human thoughts is their human rights but even now some countries have their own thinking on this like their should be a limit of expressing himself publicly. And due to these reasons twitter is backing out from few countries announcing that they have their different ideas and are not able to exists in few countries.
Mainly this decision is for those countries where government & non-government parties are against each other for revolutions. As social sites connects people to each other in a amazing way now-a-days and due to this they are backing up many protests in some sensitive areas. So the back step of twitter from such countries may disappoint many users and also may weak protests but twitter has announced that they are going to restrict their tweets in few countries while keeping tweets must flow in rest of the world.