Collymore, who has been undergoing counselling for stress and depression since walking out on the club last month, appeared for the last 19 minutes as Villa tried in vain to avoid a third consecutive defeat in the Premiership.
But despite Collymore being greeted almost as a hero by the Villa Park crowd, Gregory made it clear yesterday that there was no question of Villa extending an olive branch to the club's pounds 7m record signing, whose prospects of reviving his career in the West Midlands appear to be diminishing.
"I've said all along that I don't agree with what Stan is doing and that remains my position," Gregory said, re-emphasising that he will not be offering Collymore the same friendship and understanding he has shown towards Paul Merson in his struggle against alcoholism.
Gregory has shown undisguised disdain for the course Collymore has chosen to take and indicated that his recall on Wednesday came only because there was effectively no alternative. Collymore had not been expected to make a playing comeback until next month.
"The situation is that Dion (Dublin) is struggling with a groin problem at the moment which really needs an operation and he is playing in a great deal of pain," Gregory explained.
"In the last few games we have been so stretched I have had to put virtually the youth team on the bench. I needed someone with experience so I spoke to Jim Walker, the physio, a few hours before the game, and he told me that Stan was in good enough shape physically to play.
"As a result of that conversation I spoke to Stan at about 5.30pm on Wednesday and he said he was willing to come and sit on the bench. I told him to put aside all the rubbish of the last few weeks and get back to playing football. To be fair, when he did come on he did okay."
But Gregory was in no mood to forgive the 29-year-old Collymore, whose admission to the Priory Clinic at Marchwood in Hampshire - where Paul Gascoigne has also received treatment - followed his refusal to sit on the substitutes' bench for Villa's FA Cup match against Fulham last month.
Nor did he make any attempt to withdraw any of his outspoken criticisms of the player, whom he holds at least partially responsible for the slump in form that has seen Villa lose four matches in a row, starting with the Cup defeat against Fulham, and surrender their place at the top of the Premiership.
In Gregory's view, the latest controversy surrounding Collymore has done nothing but undermine Villa's progress. "So much of my attention has been taken up with these off-the-field affairs at a time when I would have preferred to be out on the training ground," he said.
Collymore returned to the clinic after Wednesday's match and is expected to stay there for at least another 10 days, although there is a possibility he will play some part in Villa's match against Wimbledon at Selhurst Park on Sunday.
"Stan is very positive about his treatment," Gregory said. "He says it is helping him and if it helps Stan then I suppose it helps Villa, in a small way.
"But I am still very sceptical about the whole issue," he added. "I'm of the old school, if you like. I prefer my players to roll their sleeves up and get on with life. It is not a very pleasant situation for me to deal with but it is something I inherited and I have no control over it."
Despite Wednesday's truce, Collymore's future at Villa Park is unlikely to involve more than a bit-part role and Gregory has made it plain more than once that he would prefer to sell him.
"I think maybe this is his best role, as a substitute," Gregory said. "When he came on he definitely gave the crowd a lift and the players on the field a lift.
Whether Collymore would view that as the future he is looking for remains to be seen.Reuse content