Re: decision regarding Rugal incomprehensible!
It is interesting how they make the exact opposite decision in that episode as Picard did with Jono. This implies to me that the decision in that episode arose out of 'Human guilt' rather than moral imperative.
Although in Jono's case, his human parents were both dead.
Sisko returned Rugal to Cardassia because Kotan Pa'Dar was still alive. Jono had no biological parents to return to.
"A hot dog at the ballpark is better than a steak at the Ritz." - Humphrey Bogart