I'd hope he's doing what he can to get him out of there. Not sure what that looks like given the fact he's still in a relationship with the children's mother, but doesn't live there. Does he just exercise his parental rights and say he's taking him? I'm sure the mother wouldn't be on board with that, given she's just lost one child.
Another potential way to interpret that the father thought it was "dangerous" (if indeed true) could indicate hoarding inside the home. That would pose a danger to a toddler and a pre-schooler, given the things they could touch, eat, inhale, get injured on etc.
MOO