Samoa won the lightning-interrupted clash 34-6 at Suncorp Stadium, which started with fire and brimstone in front of 44,682 fans.
Molo collected Utoikamanu, playing his first game for Tonga after previously representing Samoa, flush in the head.
Utoikamanu was ruled to be a category-one HIA and he did not return.
Molo was penalised for the incident and put on report but remained on the field.
The NRL Match Review Committee deemed the incident to be a grade-two careless high tackle, but the Dolphins prop is free to play in the final on November 9 in Sydney with an early guilty plea and a financial penalty of 13 per cent of his match fees.
Tonga coach Kristian Woolf did not blame the incident for the loss, but said the fact Molo stayed on the park and was not punished was an anomaly that needed to be addressed.
"It is not why we lost the game. We got outplayed today and Samoa were outstanding," Woolf said.
"It is something we need to have a look at, here and in club-land I suppose, if you have a player that has got to go off for foul play and can't return.
"It is not just that you lose a player. You lose an interchange, and there is not much repercussion the other way."
Utoikamanu is now set to miss the clash with New Zealand in Eden Park on Sunday, which Tonga must win by 17 points to advance to the November 9 final against Samoa in Sydney.
Woolf floated the idea that Tonga may ask for dispensation to challenge the ruling after Samoa hooker Jazz Tevaga was rubbed out of the 24-18 loss to the Kiwis the previous week.
Tevaga's head knock was not categorised, but he took no further part in the match after showing concussion symptoms.
The NRL reviewed the incident and allowed Tevaga to play against Tonga after their chief medical officer gave him the green light.
"I don't know where (Utoikamanu) is at for next week or whether we are a chance of challenging that," Woolf said.
"I know Samoa did last week with Jazz Tevaga and overturned that. But there is potential for him to miss two games basically because that (incident) happened in the first set of the game."
The NRL told AAP that Utoikamanu, unlike Tevaga, had been ruled a category one. His chances of having the decision amended appear slim.