1 Content can't be "banned" from the blockchain - at most it can be downgraded in visibility on the front-end layer (the website that displays the contents of the blockchain)

2 The lack of clarity may be a result of non-uniform laws across the globe. What is legal in one country may be illegal in another. Entire networks or mail providers are affected in some cases where their operation is banned in a certain country. Even youtube has been banned in some countries. The emergence of a clear-cut "guideline" may not happen for years to come, if ever, in part because of the global differences in their legal framework and in part due to the difficulties involved in enforcing anything at the level of the blockchain (which is not very desirable).