I wasn't aware that Brueckner's MO included kidnap or murder either.
Everybody has to be caught for the first time. Until a couple of years ago, you could have claimed Brueckner’s MO didn't include rape. Yet now he's been convicted for that offence, and it happened 17 years ago. The videos that his acquaintances found show this wasn't a one-off either. Plus there's now another rape case he's quite possibly about to face charges for, which happened 18 years ago. So little was it known that Brueckner’s MO involved rape all that time, and it would have likely remained unknown today if it wasn't for BKA starting the Madeleine investigation against him.
The point is, despite not YET having a murder or kidnap conviction, all the markers are there. Add to that his webchat fantasies where he says how much he wants to kidnap, torture and kill a child, can you really be sure his MO does not include these crimes?
Also worth pointing out that he dragged a young girl into the bushes to sexually assault her before letting her go when she began screaming. And he's being touted to be charged with Portugal beach assault, where again, the perp dragged the girl away to a secluded area to abuse her before her family found her and he ran away. Are the MO's of these crimes dissimilar to an abduction? What would have happened if they hadn't managed to get away?
If he is convicted for the beach assault one, I think that could be quite significant as it happened only a few weeks before Madeleine disappeared. It would show his mindset at the time. How frustrated would he have been that his attempts to satisfy his perversions were thwarted? Any defence that relies on him claiming he was in a happy normal sexual relationship at the time, and not interested in abusing children, would be undermined by this event. Just as his rather ridiculous claim he would not do things like this as he was too concerned about attracting attention to his drug dealing business.