The 20-year-old defender was loaned to the Saints but failed to figure in the 16 either before or after boss George Burley left to take the Scotland job.
The decision left O'Neill seething as several other clubs had shown an interest in the Republic of Ireland international, who is still to make his competitive debut for Villa.
O'Neill told the Express & Star: "He had a very frustrating time at Southampton where he didn't play.
"Stephen is in real need of games now. He didn't play down at Southampton, he's come back now and I'd certainly look at sending Stephen out on loan for 28 days."