The vaginal swabs have not been tested, and even though he did not ejaculate, it is still possible it is his. I agree, if it's not I don't see how the threshold of "beyond a reasonable doubt" could be met.
With the other evidence in her panties and the microscopic amount of blood on his shirt
The blood streaks on his shirt were not microscopic. Transcript links are available on the thread.
Then why didn't the detective say he saw them with his naked eye???
Did you read the cross? Notice he insinuated he SAW the blood until Mackey asked him about it?