Keogh hits out at Gonzalez
Gonzalez was sent off for elbowing striker Doyle and causing a head wound which needed five stitches in the Republic's 1-1 draw with the World Cup-bound Central Americans in Philadelphia during the early hours of Saturday morning.
His actions were swiftly condemned by manager Jorge Luis Pinto, but Keogh admitted he was astonished by the incident, which happened as the two men fought out an increasingly physical battle.
The 27-year-old Derby man said: "We knew it was going to be a tough game, but I suppose in a friendly, you are not expecting someone to elbow someone in the head.
"You wouldn't expect that in any game, let alone a friendly game. He's got stitches in there now, Doyler.
"It was stupid, he deserved to be sent off. You don't want to see that on a football pitch. I hope he learns from it because he has let his team-mates down and let his country down.
"It was a poor challenge. If you look back at it, even their players were apologising for it.
"It was stupid, very stupid. I don't know what went through his head, but he deserved the red card."
Skipper Robbie Keane did not get a good view of the incident, but its after-effects told him all he needed to know.
Keane said: "I saw the two guys going up, but I didn't really see it very, very clearly.
"But it's clear to see from his [Doyle's] injury - he's in there now getting stitches - so it certainly was a bad injury."
Ireland were leading through Doyle's fine 18th-minute header when Gonzalez departed, but the visitors' response in adversity was impressive.
Sparked by the excellent Joel Campbell, the Arsenal midfielder who spent last season on loan at Olympiacos, and striker Brian Ruiz, they worked their way back into the game and levelled when Celso Borges converted a 64th-minute penalty.
Keane could have won it for Ireland within two minutes when he too was handed a chance to score from 12 yards, but substitute keeper Patrick Pemberton, who would go on to make vital stops from Shane Long and Simon Cox at the death, palmed away his effort.
Martin O'Neill's men will complete their season with another tough assignment against Portugal in New Jersey during the early hours of Wednesday morning, but Keane insists that is just the kind of challenge they need to hone themselves for the start of the Euro 2016 qualifying campaign in September.
He said: "It's important that we play good teams and certainly teams who keep the ball and have good possession because come September and playing in the qualifiers, we are going to be playing against teams that are very, very good on the ball.
"At times, we are going to have to be sitting back for 10, 15 minutes and trying to soak the pressure up."
Keogh will hope he has a part to play against both the Portuguese and Georgia in the opening qualifier as he continues the process of coming to terms with his play-off final disappointment.
He said: "I was pleased how it went. It was good to be back out there - it's the best thing you can do, really, especially after how the season ended.
"I have always been confident I can play at this level. I am still young, I am still learning all the time.
"It was a cruel way to end the season after a really good season both personally and for Derby, so the best thing I did was meet up straight away and try to forget about it.
"All these guys have been absolutely fantastic with me and made me forget about it a little bit. I am happiest when I am out there playing football."