I don't think the internet, broadband companies are interested in blocking any particular segment like political parties, religious sites, etc..

The blog post or at least the quote makes a good point that it could be unconstitutional. Being a little bit similar it reminds me of what happened to us in the UK:

When the radio broadcasting companies had to stop broadcasting content over the internet because the artists wanted more royalties and the radio companies were losing money because of their business model didn't account for so many listeners.

In the end the radio internet streams were turned off - and some such as the BBC decided to filter the traffic that was watching/listening to their content.

The UK had become the only developed country to prohibit its citizens to access foreign media, besides China!