Kneeling in front of Horn, Rushton asked the fighter a couple of times: "What do you want to do?"
When he didn't answer, one of the those advocating for a retirement said: "That says it all."
But Rushton continued, asking Horn if he had one last effort left in the tank.
"Have you got a punch left in you or not?" he said. "Do you want to give us a minute?"
Australian boxing legend Jeff Fenech was in commentary and couldn't believe what he was hearing.
"Oh my God, of course he's stopping," Fenech said, just before the fight ended. "Of course they have (stopped).
"To hear that corner argue about (stopping), when Jeff Horn couldn't even answer if he wanted to fight, to tell him to go back out is disgraceful."
Co-commentator Ben Damon added: "Thank goodness sanity prevailed because we did not need to see a man who has achieved so much and done so much for Australian boxing take any more punishment.
"He leaves the way he deserves."
Main Event boxing expert Paul Kent was the most savage on Rushton, saying it was "embarrassing" to see what was happening in Horn's corner when everyone could see he was out of steam.
"For Glenn Rushton, who is Jeff Horn's trainer, to be sitting there at the end of the eighth round asking if he wants to fight again, whether he has one more punch in him, whether he has one more minute in him, was absolutely embarrassing to be honest," Kent said.
"It showed the amateurism that's been in Jeff Horn's corner for much of his career.
"The greatness of Jeff Horn is he's been able to overcome that.
"I think this has been a handicap he's had to deal with his whole career and it's a testament that he's been able to have such success with that."
Kent also slaughtered the advice Horn's camp gave the southpaw during the fight. He said their tactics were at odds with reality after Tszyu took the upper hand from the first round.
"He (Horn) was constantly being given bad advice from early in the fight," Kent said. "He was gassed after two rounds and he was gone and yet already by round three, Tim Tszyu was stalking Jeff Horn, looking for the shot.
"Yet when he goes to the corner, Glenn Rushton was telling Jeff Horn that he's got to walk up and be first, that he's got to push the pace against Tim Tszyu.
"The fight was over by then, he was in survival mode. To be told by his corner that he had to lead the fight, that he had to lead up on Tim Tszyu, it just astounds me.
"He clearly wasn't fit enough for this fight, so he'd been pushed into this fight when he wasn't fit enough to fight 10 rounds.
"He was gone after two rounds, and his corner should have known that."
