Being firm and giving an order are two different things. As Angra asked for protection Satoshi has to give it, given the situation at hand he very obviously doesn't want to leave his family. As such, because Forest is, as Lancer puts it, the "Landlady" Satoshi has to discuss the issue with her.
it's not an order, it's a point of basic decency. He can't just say, yes you can stay here, he has to ask first.