People keep saying this, and while I'm sure a fight between Ian and Axel will happen at some point, I don't think it will be at the tournament.
Firstly, they are simply in different weight categories. And I don't think that will ever change, even if the "fit" variable reaches a score of 2 or higher, especially since it is more likely to have the opposite effect: Ian is becoming leaner and more muscular, i.e. his body fat percentage is decreasing, while his weight is changing insignificantly.
Secondly, I don't think Axel practises martial arts, although I admit that he may have done so at some point. He is a bodybuilder (and most likely uses steroids), and like Jack, he relies on mass and size. And in all his confrontations, the most he does is push someone or throw a sucker punch. And if Ian is highly skilled in jiu jitsu, Axel can't even push him. He is certainly strong and dangerous, but not because of his skills.