The Australian-born siblings were due to meet head-on in Saturday’s showpiece but St Helens’ Sione Mata’utia has been suspended.
The RFL disciplinary panel charged the back-row with two offences in Saints’ win over Wakefield Trinity last Friday.
The 25-year-old had a charge of dangerous contact downgraded after an appeal but failed to overturn another one-match ban given for a high tackle.
Elder brother Peter, 30, who will play centre for Castleford at Wembley said: “I spoke to him last night. I found out online.
“He is pretty gutted, to be honest, and angry at the same time.
“I’ve seen him work hard since being a young kid and I can’t think of anyone else who deserves to be on a stage like Wembley this week (more than him).
“We had a good chat. He knows it is what it is and we know Saints will always be there somewhere every year so he’ll get another shot, no doubt.”
Growing up in Australia, Mata’utia witnessed domestic violence and spent time in home shelters, his mum working two jobs to try and provide for seven children.
“I was pretty buzzed for it to happen,” he said, with regards meeting in the final.
“For me to be there is pretty exciting but to see my brother as well…
“We’ve had a tough road getting to where we are and being able to see him there would have meant all the sacrifices that my mum made when we were little were still paying off.
“But things happen and he’ll get there another year.”
Mata’utia, who regularly undertakes volunteer work around Castleford and uses social media to promote mental health awareness, added: “I got to speak to one of my mentors yesterday.
“He said it is disappointing my brother won’t be there but this probably is my time. My turn to have a crack.
“At the same time, it’s a good thing for us he’s not playing as well!
“They’ll be a great team without him anyway. We’re looking forward to the challenge.”
St Helens arrive as big favourites but Castleford, who have seen two of their last three games called off due to Covid while the bulk of their squad has not played for three weeks, showed in an epic semi-final success over Warrington Wolves what they can achieve.
And Samoa international Mata’utia, who joined Daryl Powell’s Tigers from Leigh Centurions in 2018, said: “I’ve only got two wooden spoons to my name so I wouldn’t mind adding a trophy!
“I know we haven’t played for a while but we’ve been putting in the reps at training.
“We’ve had a few games of 13 v 13 and we have no excuses for Saturday. We want to make the most of this.
“Like I said in the first lockdown last year, this club deserves something. They were close in 2017 (in Super League) and I’m excited for those who are leaving and those who have been here 10 years plus. I’ll be doing all I can to get this trophy.”
Castleford, of course, have not won the Challenge Cup since Malcolm Reilly’s side prospered in 1986.
As a player, the formidable loose forward Reilly won the Lance Todd Trophy when Castleford lifted the Cup in 1969 and played again when they defended it 12 months later.
A Castleford legend, he also earned fame Down Under, first as a player with Manly but also when coaching Newcastle Knights for four years and guiding them to their first Grand Final glory in 1997.
Mata’utia made his NRL debut with Newcastle in 2011 and, after three years with St George Illawarra, he returned to the Knights for a couple more seasons in 2016.
Sione played more than 100 games for Newcastle before joining Saints this year while Peter’s younger brothers Pat and Chanel also represented the NRL club.
But, bizarrely, Mata’utia – who follows Powell to Warrington in 2022 – never realised Reilly’s significance here.
He said: “I’m from Newcastle where Mal Reilly is very well respected.
“But, to be honest, I didn’t know he was English or from Cas until I got to Cas!
“I saw his name on one of the benches at Carlton Lanes (shopping centre) and I couldn’t believe my eyes.
“I remember messaging Powelly and asking ‘is this the same Mal Reilly who’s from Newcastle?!’
“That’s the first time I found out he was English and from Cas!
“In Newcastle they call us the steel city; it’s a blue collared town, a one town team.
“When you talk about Mal Reilly, you come through as a kid there learning about what the club is based on and it’s being a player that others want to play with like Mal.
“I hold Mal up there as he gets spoken a lot about back home.
“It’s weird to find out he’s from Cas and I end up here. I talk to my brother at Saints and get pretty emotional just talking about him as he means so much to us back home.”
If his side win the Challenge Cup on Saturday, Mata’utia will garner similar status in his adopted home – and forever mean so much to Castleford fans.