Who knows why this, in particular, triggered his schizo wet brain, but at the start of the rant, he does mention his children leaving it in a disgusting state. From comments Nicki had made before, plus with recent revelations from that Steel Toe faggot, it's clear that they all live in a pigsty, and the Rekieta's have long ago given up on trying to discipline their children.
Just in the last few pages, we have clips of Aaron complaining about having to tell the kids to clean up when he's there. Nick often makes little side comments about all the junk around the house left by the kids. When Lady Rackets got that little dog, I recall Nicki often talking about the kids and Lady Rackets herself not wanting to clean up after the dog, let alone any of their other messes. The kids have no discipline nor a role model on how to behave. Dad is a sloppy, drunken faggot whose own streaming office is filled with junk. Mom is zoned out on pills and can't even cook, let alone clean. The few adults who try and step in and provide guidance on how to act, such as the bible school lady, are undermined and criticized by Nick because any discipline by others triggers his PTSD of Transformer figurines being taken away, and he's too lazy to discipline them himself and probably copes by thinking he's being a cool libertarian dad.