Kevin Nisbet headed Hibs ahead in the eighth minute before center-back Porteous was shown a straight red card by referee Nick Walsh on the half-hour mark for a hefty challenge on the Gers attacker.
Hibs withstood increasing pressure from Rangers until the 59th minute when substitute Kemar Roofe levelled with a header. Colombia striker Alfredo Morelos then grabbed a dramatic winner for the hosts with 11 minutes remaining to take the champions one point clear of Hearts at the top of the cinch Premiership.
Gers boss Gerrard told Sky Sports that his side “were rewarded for all our good play in the end” before switching his focus to the turning point in the game.
He said: “I know one or two things about bad tackles because I have made a few myself, so I am not in a glass house here.
“It’s a wild tackle. It’s a leg-breaking tackle if he catches him.
“The kid only has to play the ball.
“I don’t know why there is any reason that he wants to go in with that intent and it is the second time that he has done it against us because he done it against Lassana Coulibaly not so long ago.
“So the kid is obviously not learning and he has let his manager and his teammates down today.
“That is obviously Jack’s (Hibernian manager Ross) business.
“There is no defending a tackle like that because the speed of it, the height of it and the force don’t belong on a football pitch.
“I have had to learn over the years myself as a player to learn from those types of moments of madness. So hopefully the kid learns.”
Hibs boss Jack Ross was not entirely convinced about the sending off but admits 22-year-old Porteous will have to learn.
He 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 is 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.
“He’s got my absolute support. He has made strides in the last year and a half but he’s going to have to learn from this one again today.”