I tend to think when all is said and done, we won't say "the big bang happened x billion years ago...."
We will say "We are now in the x billionth year of the bang..."
It sounds like a semantic ploy, but I think there's something different to it.
I think you are correct. The effect of the Big Bang is still underway, thus the expansion of space.
I especially like the "from the big bang up to the present day and into the unforseeable future" part, implying that they have exactly what happened at the beginning down cold.
I suppose that theories are like that: once you are working on another one, the preceeding ones become "fact."
When I read it in News of the World, I'll believe it.