Would you rather the agency detained the parents but not the children? Splitting up families is worse than detaining children in my opinion. I'm sure you'd think that detaining anybody is bad, but then what is the point in having borders if you don't enforce them? A law that isn't enforced is not a good law. Or maybe you disagree with borders too? In which case supporting any US government since the creation of the nation has been an "abuse of power" too?