He might have thought very differently had the game not finished up as Everton's first win at Old Trafford since 2013 – ironically when Moyes himself was Manchester United manager and Bryan Oviedo scored the decisive Toffees goal – but the Scot claimed he saw a major positive in the Gueye flashpoint because of what it represented.
"There's another side to it," Moyes said. "I like my players fighting each other, if someone didn't do the right action. If you want that toughness and resilience to get a result, you want someone to act on it."
On the actual decision to send Gueye off in the first place, Moyes added: "If nothing happened, I don't think anyone in the stadium would have been surprised. I thought the referee could have taken a bit longer to think about it. I got told that the rules of the game are that if you slap your own player, you could be in trouble.
"I'm disappointed we got the sending off. But we've all been footballers, we get angry with our team-mates. He's apologised for the sending off, he's praised the players and thanked them for it and apologised for what happened."
Sky Sports co-commentator Gary Neville disagreed with the decision to send Gueye off: "How much venom was in that slap? He has been sent off for that. Was it a little slap or a proper whack? There is no doubt a hand comes out to the face but it didn't look too much. They might have had to send him off purely because there is a strike to the face. They were not fighting, it wasn't a scrap. It could have been dealt with by a yellow. I don't think it needed to be a red."