How do you think Discord got freed from the statue?

Well celestia and luna trapped him in the statue but after they seperated, the statue was getting weaker and when the CMC were arguing in front of the statue, the arguement make the statue become more weaker allowing dicsord to escape

Well I think what happened was that when the cutiemark crusaders where arguing which started to help him escape than his daughter screwball helped him.

well when nightmare moon destroyed the elements the bond on discord was broken, at that point all it took was a little chaos to release him from his prison, the CMC's fight, though pathetic, was all he needed