I've been trying to figure out why in fuck's name Nick would invite a paedophile to come and be a spectator to his wife's public humiliation, in which she's forced to acknowledge showing her breasts to somebody else's husband while he attempts to work, while her own Christian husband snorts coke, neglects the kids and attempts to bang a Minnesota 5 skank while he struggles with erectile dysfunction.
The only possible thing I could come up with is this: he's terrified. He's shit scared that the Toe is going to bear down on him with his Louisville Slugger and he won't know whether to embrace it or to run. Presumably he's hoping Melton will be able to adequately satisfy our wife prior to the hearing, and that might stiffen her resolve somewhat, preventing her from breaking down and admitting that Aaron was her one true love and the only man who has ever satisfied her, but I think he's more worried about himself than he is Kayla.
So his plan is that if Aaron does approach him in an attempt to confront him about his behaviour, he'll be able to mince behind the obese paedophile in the hope that Porky will provide some cover from the blows that the Pugilist would be raining down on his head (which I think is how this plays out in his fevered homo-erotic court room fantasy.)
Then, after Aaron has beaten him into a pulp, he sweeps him up in his arms, admits, 'It was never Kayla. It was only ever you, Chaos.' And the pair of them ride off into the sunset, Brokeback Mountain style, leaving Kayla to her benzos and Melton to 'take care' of Nick's children (if you know what I mean and I think you do.)