That's a difficult decision and in the end only you can say if it is ok for you.
What I can say is that although in our case, the likelihood of the birth father suddenly making an appearance was small; and although the likelihood of bf (or his family) having our DD placed with them, if they did turn up at some point, was very small too; I worried. I worried up to the moment when our SW called to say the AO had been granted. It was a niggling uncertainty, always there at the back of my mind. I had to make conscious efforts to not allow that doubt affect my bonding/behaviour/feelings with DD. It was hard and tiring; just how tiring I have only realised once that weight was gone.
The next thing I'd point out is that in that case you mention (so sad, the adopters must be devastated) - the judge explicitly stated that this ruling should NOT be given any 'precedent' value. If that holds true, that ruling should not affect any future judgements. (I know that that didn't stop me worrying.)
Finally, all over that judgement it was argued that the case was extremely unusual and unique. I thought long and hard about how exactly it was unusual. And I think the key point is that although the BF knew/thought he knew that the child was his, he did NOT know that the child was in care and to be adopted. I believe that it is exactly this, that made that case unique. He DID know that it was his child, but he did NOT know that the child was in care/to be adopted.
If I understand you correctly, your potential linkee is different. BF is not sure if he is the father, but he does know that there are care proceedings etc. So just the inverse. On this basis I should think that the case you refer to has NO bearing on your potential situation.
Furthermore, BFs who show now interest in the first year or so are never likely to gain placement of the child with them, even if they do turn up and claim the child. Even in that case above, BF would have been highly unlikely to gain placement of the child with him. Instead the child was placed with an aunt. And again this was only thought suitable because 'kinship care' is (apparently) common and normative in the ethnic society the BF and his family are from. So unless your potential linkee is from an ethnicity where kinship care is the norm, I think you can discount the possibility that a judge would rule that the child is to be placed with a relative of the BF (after having been in your care already and application for AO submitted). And if the BF shows no interest in the child and does not cooperate with SS now, not even to establish paternity, I do not think you need to worry about the child being placed with him (after having already been placed with you, and AO application submitted).
I guess what I'm saying is, you ought not have to worry about that case setting a precedent affecting your potential situation. But then again, as I'm sure you know, there never is absolute certainty; until the day the AO is granted.