I haven't followed this thread, but I read a lengthy article about this case a few weeks ago. I have to say that I am with you 100% here, Linda - I could give a flip about "legal" parent - the stepfather is this child's parent and if I were the Dad, I'd be in Brazil and I'd have been there a long time ago.
An aside - my BIL got a German au pair pregnant 13 years ago. She went back to Germany and he followed even though their personal romantic relationship had ended. He's been in Germany ever since because he wants to be present in his son's life.
The au pair has since remarried and had two more children with her husband and my BIL's son lives with his mother and stepfather. He is, of course, very close with his stepfather, but he also sees his father all the time and is close with him and travels back to the US with his father to see all of us here at least once a year.
I will add that my BIL does not like being in German - he would rather be back in the States for a number of reason. That said, in Germany he stays because more than his personal desires and comforts, he wants to know his son and he does not want to put is son in the middle of some gruesome legal tug of war.
I have immense respect for my BIL.
SCM, did your BIL bring the whole family to Germany? I'm being nosy, so don't answer if you don't want to. But I'm curious, because if she was an au pair, then your BIL had other kids, right? So are they all in Germany, or did he leave them behind in the US?