There are a lot of gaps. But I think he fell asleep, was not in charge of watching any kids, while there were sick kids sleeping in another room as well. He gets woken up by the foster kid going ape crap and flips out on him saying people are trying to sleep. The SIL gets pissed at him for telling the foster kid to STFU.
I think he’s underselling what happened and bet he flipped on the kid for waking him up, but tries to turn it as he might wake up the sick kids.
Honestly, who rough ridin' knows what he meant with that story though.