Quote from the autopsy report where he says that.
He describes what he sees, not how it happened.
I think most people would read that as due to hemorrhage. I could be wrong, but he sees blood within layers of the BBB where it would not normally be or wouldn't drain and he describes it in the context of a hemorrhage. He describes livor mortis in other areas, so it doesn't seem like he would confuse the two. IMO.
Beyond the fact that the blood is not the result of drainage, there are several reasons why the blow had to occur while she was alive and not after death:
1.) Early brain swelling was already evident according to the autopsy (description of gyri)
2.) the hemorrhaging itself
3.) contusions on the right cerebral cortex
4.) contusions on the scalp
So, as far as I can tell, it seems pretty obvious she was alive when the head trauma occured. From everything I've seen all the experts who have spoken on it seem to agree that she was alive when the blow occured.