The Bhoys boss gave mixed reviews after a narrow win against Partick Thistle.
The Bhoys won 1-0 at Parkhead but were reduced to 10 men when Bitton went off.
Deila, though, did choose to praise substitute James Forrest, who he felt made a difference for Celtic as they secured a narrow late victory.
On Bitton, Deila is quoted as saying by Sky: "I think it was very easy, I don't think it was a red card. Having said that, it was also a little bit stupid because there was an incident before that.
"I don't think that was a yellow card either and then the other one, those two together made the decision for the referee. I think it was inexperience and something he needs to learn from."
Of Forrest, however, the Norwegian said: "Every team relies on some players, of course they do. I am happy that Jamesie came on as well and made a difference."
The general consensus seems to be that Deila was saved from real trouble by Leigh Griffiths's late winner against Partick. The Celtic boss looked relatively upbeat after the 1-0 triumph but that might have been relief more than anything.
Celtic's recent results and performances have been rocky by their standards and the one thing you don't do when you're under pressure is fail to beat Partick Thistle at home.
Deila started two defensive midfielders and just one striker against the Scottish Premiership side and the Bhoys' lack of goals was almost too easy to predict.
Next up for Celtic is a Scottish Cup clash against Stranraer, before the Hoops travel to Dundee United in the league.