It's not so much the fact that his team is the first from the Orchard county to contest an All-Ireland football final since 1977, when he was one of their few stars in the defeat by Dublin.
He says he "would have gone to his grave" regretting not taking up the challenge.
"I suppose I thought I would never get the chance. After working with Crossmaglen for 20 years, I thought it would pass me by," he explains.
"But when the opportunity came, it was something I just couldn't turn down and I'm glad now that I didn't.
"I spoke to a couple of other counties, but in hindsight it was great that I didn't get involved."
It has been well chronicled how Kernan helped to mastermind three victories for Crossmaglen Rangers in the AIB All-Ireland club championship. After Nemo Rangers (six-time champions), they share with St Finbarrs the distinction of being the only other side to win three titles.
"There's no secret," he says, casually.
"Basically, it's all about a lot of good players and a lot of hard work.
"The thing about being a manager is that you are learning all the time. In Crossmaglen, I had to do a lot of things on my own. There were a lot of good people throughout the country that I rang and asked for assistance. Even this year when I phoned people, it was an immense help. Our back-up team has been perfect. We haven't wanted for anything.
"After we lost to Laois in the League semi-final, we, as a management, held our hands up and said that we'd need to change a few things. The players, in fairness, were honest, too. The way they performed against Laois wasn't good enough."
The players credit him with bringing a "freshness" to the campaign this year. One novel idea was to take the panel to Spain for a short break. He says it got them closer together and helped them focus on their championship game with Tyrone.
"Our performance against Tyrone was a breath of fresh air," he added.
"It gave the players and the supporters the reassurance that there was a lot more left in this team. Naturally, a few new faces coming in sweetened the thing up as well.
"The players deserve a lot of credit for the character they showed. After two or three hard years, it would have been easy for them, especially against Tyrone in the first game when they came back after we played so well, to throw in the towel. We did take a bit of stick for finishing tired against Sligo. Maybe Sligo deserve more credit than we all gave them. I think we finished strongly the last day. So there is a bit of freshness back in the boys."
Beating Dublin in the semi-final was "a relief, first and foremost", he says.
"Some people believed there was a Croke Park hoodoo, yet it wasn't as if they were sending teams out of Ulster regularly and failing. Since '77, the only Ulster successes were gained in the early 80s (1980 and '82) and three over the last four years.
"It was just that we didn't 'finish' the games in previous years.
"The last day we finished with three points in the last 10 minutes. That is the difference."
He doesn't deny that it's a help to his team to be underdogs again.
"No matter whether you are favourites or underdogs, you still have to perform. What I honestly do believe now is that the boys are well able to perform on the big stage. I honestly believe we haven't seen the best of them.
"Kerry are hungry. They came out of Croke Park last year very sore after the way they lost to Meath. They had to come back this year to prove themselves, and as far as Kerry will be concerned, it might be the back door, but they are there on merit. They are there to win this All-Ireland to put last year to bed."
Acknowledging that the Kerry attack poses a serious threat "if they get ball in, we are in trouble" he
believes that their own forwards will take much watching, with an average of five and six men scoring all the time.
"Certainly, we'd love to make a good start. But if you don't, it doesn't mean you are not going to win the game. I'd prefer to finish the last five minutes better. Games are sometimes won and lost in the last five minutes.
"It's all or nothing, but at least we are here. Armagh can play better, we know that. If we don't, it won't be our day. But I have a feeling that now that the handcuffs are off and we got the win we wanted, we're going to go for this game.
"We're not going to sit back."