Clearly the Portuguese wish to keep their options open so they have chosen to be persuaded by the Germans in this instance. Can't see it going anywhere though as there just isn't any direct evidence that we know of connecting Bruckner with Madeleine McCann.
The Portuguese were left with two choices. Either designate Bruckner as an arguido or don't do so. IMO they couldn't take the risk of not doing so in case new evidence turns up.
As it stands though, there is nothing to connect Bruckner to Madeleine's disappearance, certainly nothing that would stand up to scrutiny in a court of law.
Wolters claims have not survived the test of time, nobody has come forward with that smoking gun, the truth being there isn't anyone to come forward. Bruckner is getting off on all the attention, he knows that the Germans have been busily digging one great big hole for themselves and now both they and the Portuguese have fallen into it.
Bruckner might well face other prosecutions for the rape of the Irish tour rep or for other abuse cases but he will never be tried for the abduction and/or murder of Madeleine McCann.