They had keeper Jamie Langfield to thank, however, for the fine save he made from St Mirren's in-form striker Esmael Goncalves in the dying stages, with the game teetering towards the visitors.
The game had failed to spark into life on a pitch that had clearly suffered for hosting Scotland's friendly victory over Estonia in midweek, but there was the glimmer of an opportunity when the Dons' Reynolds hauled back Goncalves, earning the game's first booking.
Gary Teale lined up the free-kick, 22 yards out and to the left of centre, but blasted his shot straight at the wall.
St Mirren's biggest threat throughout the first half had been the runs of Paul Dummett from left-back and, just before half-time, he put in a low cross which required the intervention of Reynolds and Joe Shaughnessy to turn it behind for a corner.
Aberdeen spent the first five minutes of the second period camped in the St Mirren half, albeit with only a 20-yard Jonny Hayes effort stinging the palms of Craig Samson.
The Dons fans were convinced they should have had a penalty when Peter Pawlett appeared to be pulled back by St Mirren skipper Jim Goodwin, but there looked to be very little in it, and referee John Beaton was unmoved by their appeals.
After 73 minutes Reynolds lifted an arm as he charged to block a Kenny McLean shot, with Beaton ruling it had been a deliberate handball, and so the Dons man received a second yellow card.
St Mirren had the best chance of the match as the game entered a frantic final five minutes.
Paul McGowan worked the ball across the face of goal to the unmarked Goncalves, but Langfield was alert to the danger and spread himself to block as the striker tried to lift the ball over him.