There are probably a lot of good reasons for Dad to have representation. First off, despite the endangerment charges, to which he has all but admitted, there is the presumption of innocence regarding anything else. There is likely some balancing of what he might be able to say in this court without incriminating himself in another trial in another court.
Also, I don't know that child endangering requires an automatic severing of all parental rights. Imagine if he put Sherin out under the tree at 3 AM, returning at 3:15 and brought her back in the house. BUT he was seen by a neighbor who called CPS, spurring an investigation, charges and all the same. The outcome in that case might involve something closer to supervised visitation, parenting classes and a process moving towards a more normal situation. Further, even a parent incarcerated for life may retain some parental rights (regular visits or pictures, participation in some key decisions regarding education and the like). I'm not advocating for anything here, just pointing out that things are not so cut and dried as some may suppose.
I have no idea why he didn't have an attorney with him today. Maybe he thought he didn't need one, or that his existing attorney could represent him here. Maybe he's having a hard time finding someone, or coming up with the retainer. Probably a whole lot of garden variety reasons that should be considered before leaping into some Machiavellian scheme to deprive Sini of contact.