Kevin Nisbet’s eighth-minute header had given the Capital club an early lead and the visitors were on top for large parts of the opening 30 minutes until the 22-year-old was given his marching orders for a challenge on Gers midfielder Joe Aribo.
Speaking after the match the Easter Road boss said: “As it happened, I didn't even think it was a foul but that was from my view.
"I then watched it and the first couple of angles I had the same opinion. From the angle behind the goal it doesn't look great but what I don't quite understand is that the match official’s view must be the same – he’s not watching it from behind the goals.
"But I think Ryan gives him a decision to make. I don't necessarily agree with the decision but I can understand why it's given.
"There are moments in games, whether it is penalty kicks awarded against you or you or sendings off that can change games.”
Despite having to play out the final hour of the game with ten men, Ross refused to hang Porteous out to dry, instead choosing to highlight the improvements in his performances this season.
"I know he will get criticism and stick and there will be loads out to vilify him but I think Ryan is brilliant player, a top centre-half in this country.
"He has an aggression about his game but you need that as a defender – or certainly you used to have.
"I am not going to tell Ryan not be aggressive but I think he has made big improvements in his decision-making but he doesn't need to go to ground. He has put himself
in a good position, he has read the situation well.”
Although Hibs held onto their lead until the interval and indeed until the hour mark, Ross was left fuming at the manner of the goals conceded as Kemar Roofe and Alfredo Morelos headed the equaliser and winner respectively.
"I am angry and frustrated because we came here believing we could win and we showed in that first half-hour that we could,” he added.
"The first 30 minutes I thought were excellent, really good, and we deserved to be ahead and were in a good place in the game.
"The sending off was the defining moment of the game, not necessarily because you can't win it from there but 60 minutes on that pitch against a good team is tough.
"I am angry at the manner of the goals we conceded, I told the players that. Because we are a good team who are very close to being a very good team and that's the last jump we need to take to continue this progress.
"We came here with belief we could win here and we gave a performance in the first half-hour that showed that.