Masuaku himself clearly regretted his actions following the final whistle as he took to Twitter to issue an apology to everyone impacted by the incident.
Spitting has always been seen as quite possibly the worst form of retaliation in a match, and Masuaku deserves all the punishment he gets.
Speaking to SkySports, he said: "Ultimately, Arthur, what he's done, was despicable".
"It was despicable. I've not seen it from him".
"We gave him a chance, he wasn't really in the team".
With spitting comes a mandatory six game ban, so the earliest Masuaku can expect to return is the middle of March.
"I am very sad because the manager and coaches have put a lot of faith in me".
Grigg converted a second-half penalty to secure a place in the fifth round for Wigan, while West Ham's misery was compounded by an injury suffered by Pedro Obiang.
"We want to bring people in who can someway contribute between now and the end of the season, if not longer", he added.
"We'll need to get over this quick and get on with it, but that's the job". So it was the players' reaction that got him sent off. "It's very disappointing on my behalf, because I want to perform and losing 2-0 at Wigan is hard, so I'm struggling for positives".
With their victory, 2013 FA Cup winners Wigan extended their unbeaten run in all competitions to 15 games.