Does it matter?
AFAIK, the only specimen the FSS tested for blood was a sample of plant from the garden and they did not find any.
Plus Grime chose to explain Eddie's response by saying it might have an origin elsewhere.
There is nothing that would stand up in a court of law that there was a dead body in 5A.
I agree that there is no evidence "that would stand up in a court of law that there was a dead body in 5A" but the intelligence it gives the investigators (from the bedroom alert) was that there was the possibility there had been a dead body that had been dead for more than a couple of hours.
So if you are looking at any surface and there clearly isn't a body on it at the time of the 10:00 Kate's alert "there was the possibility there had been a dead body [on that surface] that had been dead for more than a couple of hours".
In other words it implies that whoever died (if it was a deceased person) had to have died earlier in the night, or died later and was missed during the search.
To explain how a deceased person could have been in the apartment but not found during the search is the reason why the sports bag features in all the inquiries, for maybe the insides of sport bags were not checked by the PJ immediately after they arrived.