Deila believes the tackle, late in the game, was borne out of frustration as United slipped to back-to-back defeats against the Hoops following their Scottish League Cup final defeat on Sunday.
Jason Denayer, Leigh Griffiths and Kris Commons ensured Celtic’s grip over the mini-series against the Arabs continued before Anthony Stokes and McGowan saw red.
Virgil van Dijk grabbed a late fourth.
“It is stupid to tackle like that on the sidelines. We need to get that out of football,” Deila said after the game.
“It is a youngster standing there with a little trick.
“You can either stay or go in with both feet, as I see it. You can injure him for life.
“But I have to see it one more time. He must be frustrated, that’s why he did it.
“There were some angry and disappointed players. I spoke a bit to Stokesy, he got a knock in the his mouth and was bleeding in challenge with Paton and he reacted.
“I have to see it again to see if it was a red card.
“But I was delighted with the game.”