In Tomas MacCurtain's role as one of the leaders of the Volunteers he may have been aware of Quinlisk and may have OKd his removal, but where is the evidence? In my opinion he was otherwise engaged in the day job.
Let me paraphrase Mick Murphy's statement made in 1956.
The Council of No1. Cork Brigade, leader Sean O'Hegarty, decide Quinlisk was to be shot. MM says it occurred on 25 Feb 1920 but the correct date is 18 Feb 1920. MM met Q by agreement the latter was asked to assemble a Hotchkiss gun and there would be £10 in it for Q. Later that night a man named Keyes brought Q to Curragh Road. Frank Mahony 2nd Battalion Intelligence Officer and Jimmy Walsh, local Captain turned up with MM.Keyes was sent home. The others walked through fields in the dark supposedly heading for the cottage wher the Hotchkiss was.MM stuck his .45 Colt in Q's back and ordered hands up. They searched him taking letters, cigarette case and newspaper cutting. "We shot him standing there". As it was approaching curfew the decided to leave but MM thought he would check, went back and hit Q with the butt of his Colt, the body moved, MM turned him over and put a bullet through his forehead. That night following a raid on the mails they found a letter from Q addressed to the County Inspector, RIC, stating Q had been in touch with a prominent IRA officer "meaning me, I suppose" who had told him Michael Collins was in Clonakilty Co Corkand this IRA officer was to introduce Collins to Q. when Collins arrived in Cork City.
Among the documents found on Q was a letter to the RIC saying Q had information on Collins and would be in touch again. In his cigarette case was a cutting from a Wexford paper"Daring rescue from the Nore". - a boy had been rescued from the River Nore by a John Quinlisk.
All this data was notified to GHQ in Dublin. Word came back that one of Collins's sources in Dublin Castlehad found Q's application for service as an agent of Dublin Castle and also his acceptance as such by the Castle.
The local newspaper in Cork City carried accounts of the shooting and the inquest held on 20 Feb 1920. By which time Q's identity was still not known
Throughout all this time MM thought his name was Quinn, the name he used in two Cork hotels.