Re: "prevent the use of digital infrastructure for surveillance"
I'm not sure what your point is. Mine is that they clearly haven't thought any of this through and should be seen as a bunch of incompetents looking for headlines. Spooks will use the infrastructure for surveillance, as they always have, regardless of whether or not they have special dispensation. Private companies, who's entire business model relies on surveillance, will no longer be able to operate legally in the UK (or will need to operate in a manner which drastically reduces their profits.) Therefore it will not be possible to raise (sufficient) taxes on their profits. That's before we get into the practicalities of whether public or private ownership is more capable of running the whole thing, or which is more likely to result in wider coverage in the longer term.