The 26-year-old was a powerhouse in the 30-26 win over his former team on Saturday night in an 80-minute display as he ran for 164m, scored a try and was up to his neck in all the side's good work.
Su'A was left out of the Maroons side for the Origin decider on Wednesday night after playing in the 38-18 loss in game two.
He had earlier returned to the Origin team in the 38-10 win in game one after a three-year Maroons absence.
"I was disappointed (to be dropped), but that's just the way it goes and the way the ball rolls and Billy (Slater) knows what he's doing," Su'A said.
"Just spending the two camps with him, it was crazy the knowledge he has and I'm really fortunate and grateful for him to give me those two games.
"Look, I was disappointed. I was more so disappointed for my family. They ride the highs and lows and that was upsetting.
"They really wanted me to play well this weekend (for the Dragons) and I kind of did that, kind of didn't, but we got the win."
Su'A said he was confident he would play Origin football again.
"Yeah, definitely," he said.
"I was confident that I could get back to that stage and I got back there and I haven't lost any confidence not being there for game three.
"I'll do whatever I can to get back to that team.
"It's a special team and it's obviously something that all young Queenslanders strive for.
"(Playing Origin) was probably my biggest motivating factor going into the year and I got there, but I didn't stay there, which is disappointing.
"It's just about getting a bit more consistent and working on a few things I need to work on."
Slater said Su'A was "nursing a few issues as well as getting scans on an issue he picked up (against Sydney Roosters)" when explaining his omission for the Maroons.
Su'A had a scan on a quad injury on Monday but said he was fine to play against the Broncos.
He played a key role in getting the Dragons provisionally in the top eight. Now he wants to keep that momentum going and ensure the Dragons play finals.
"It's huge, that's honestly my biggest goal now, getting this great club back to where it belongs," he said.
"I think we've got the team to do it.
"We've got the coach (Shane Flanagan) to do it.
"Everyone believes in the systems we have in place this year and I think we can surely do it.
"We've got a few things to work on. If we don't believe in ourselves, who will?"
