Dear Timothy
Ok thanks for that, I'd missed this divergence in your discussion. It seems quite problematic: it seems to mean inter alia that this radiation does not have a well defined stress energy tensor, so its interaction with any other matter or radiation will be ill defined.
So here's a question: does this radiation gravitate? If not why not?
It seems to me you run into the vacuum energy problem that is such a major issue in the standard view (see Weinberg's review paper in Rev Mod Phys 1989 for example), only maybe in a worse form because you are claiming there is an actual divergence.
George Ellis