Why would Logan stay with an innocent family while in danger?

They acknowledged this detail. When he put Charles to bed, he says something along the lines of, “We shouldn’t be here.” They knew they were putting that family at risk.

The purpose of the family episode is that it gave them one last moment of happiness (didn’t Charles say it was the greatest night of his life, or something?). With all that was going on, with Charles’s dementia, with Logan’s poisoning, with all the friends and family who have died, with all the hopelessness — that they would put that innocent family at risk for one great night shows how much they wanted, or needed, that joy. Just one last time.

Again, they knew they weren’t doing good for the family. But they needed that moment of happiness so bad.