In order to prevent porn and fraud sites from being accessed, they're uploading exhaustive lists of those sites to everyone's computer? Somehow this seems like it won't work out.
As far as I know, there are ways to do that without revealing the websites blocked (for example bloom filter, with a note that it can have false positives, or just the hashes of the domains)
I think the catch is more that it will be hard to keep an exhaustive list.
I'd like to add the whole government misuse angle too. People roll their eyes sometimes but It Could Happen Here. History has not ended, that's just a comforting delusion at this point.
'roll their eyes'. Even if they (the government) didn't try to misuse it, lots of sites will end on it accidently or by deciding individuals that have an agenda. And it suspect it would be a nightmare to get your site off it.