I would assume CPS in the context of drug addicts are not just worried about basic living conditions, but also about neglect by the parents.
I would be worried about the child of an alcohol addict, let alone an opioid addict.
But this is just an assumption; I don't actually know of any statistics correlating addiction with neglect.
Living conditions here was just shorthand for the existence of "they could be your neighbor and you just don't know about their drug habit". Addiction of any kind does increase the likelihood of neglect, but my point is that it is not intrinsically harmful to the child and absolutely is not enough reason to remove a child from the home.
I would wonder though how many opioid addicts are more addicted for literal pain relief reasons, to give a bad comparison someone like House on the TV show. In that case I could see it working out fine, that's much more like buying pain medication illegally because you can't afford or can't see a doctor for some reason.
CPS doesn’t draw a distinction between living conditions and neglect. They are only supposed to look for neglect and abuse, including placing children in unsafe situations. Their guidance documents are full of statements like “it is not neglect for children to share a bedroom.”