Former assistant referee Darren Cann, who officiated in more than 1,000 professional matches, described the clash between Gueye and Keane as “unusual”.
Speaking to BBC Radio 5 Live, he added: “Tony Harrington was looking directly at the confrontation. He had an unobstructed view and clearly saw Gueye slap Keane around the face, so in the laws of football that would constitute to violent conduct and a red card is the right decision.
“For Michael Keane’s push to be violent conduct, it would need to be on the face as opposed to on the chest.
“Of course you can still be sent off if you punch somebody in the chest, but I would suggest that Keane’s push away was more him telling Gueye to get off him.”
Former Everton boss Roberto Martinez, speaking on Sky Sports, said he was “very surprised” at the clash.
“There is a bit of a misunderstanding between them,” added the Portugal boss.
“The referee has no choice, the law tells you that is a red card.”
Former Liverpool defender Jamie Carragher, also speaking on Sky Sports, added: “We are talking about a slap. Can the referee manage the situation [differently]? When you look at the laws, it gives the ref an out.”
