Cornwell was charged with stamping during Gloucester's 19-8 victory on Saturday, November 26 but was cleared of the offence.
Gloucester's head coach Dean Ryan told www.gloucesterrugby.co.uk. "We had a good idea that this would be the outcome and I am delighted in the process that was followed.
"We attended the hearing and I fully support the disciplinary process. Naturally I am very pleased the decision has come down on our side and from our point of view that matter is now closed."
Cornwell was warned about his future conduct by the panel but Blackett said: "There is no criticism of the citing being brought but the panel felt the offence did not break the red card threshold.
"The test is: if the referee had seen the incident, would he have sent the player off? In our view, if he had seen the incident it would have warranted a penalty or yellow card at most.
"We therefore decided to take no further action but warned the player as to his future conduct. He is free to play immediately."