It was a decision that surprised pundits, enraged Dragons supporters and frustrated Tiatia, whose side have not won since the first game of last season.
“I thought it was a yellow card, a second one (for Penny) and it should have been red,” Tiatia said.
“I saw it differently to Morne, who I thought had a good game. There were seven points difference at the time and then the big fella (Snyman) took his chance down the right and it became 14.
“I was disappointed for the players because Leinster had dominance at scrum, but they fought hard to get back into the game and held them up numerous times over the line.
“I felt for them. We held Leinster at bay, fought hard to stay in it and we had opportunities to score points that didn’t quite happen.”
Dragons drew with Sharks and Ospreys in Newport in the first block of the URC and their resilience earned a chance to push for a share of the spoils with the champions, who have now won the last 15 meetings between the sides.
“I said in the huddle that I was proud of the performance because we had a lot of young guys that came on and got exposure at this level,” said Tiatia, who was without five Wales internationals because of Saturday’s Test with South Africa.