I think we all get the gist of what you're saying! While you like the characters of Minsc and Tiax (and seriously who doesn't), who are anything but mature, you certainly would never want to romance them! It makes sense that the person the PC would choose to romance would be mature; they are in an adult situation and carry with them more than a little baggage, and their beau would have to be able to help them cope.
From what I have seen so far with this mod, I believe Aklon will do just that.
First off, he's a little older, late thirties i think?, and that in itself adds to his maturity. And then there is the fact that he is enslaved when you find him, which most certainly hardens a person and takes away any remaining innocence (which is reminiscent of when PC and Imoen are tortured). Anyway, I guess what I'm trying to say in an extremely verbose way is that it just makes sense that Aklon would be a more mature character given his background. Now, whether that extends into anything that deserves a "mature rating" is up to BigRob, and I guess all his loyal followers as well.