Grooming is when you isolate or lie to a child or build a relationship with a child specifically with the intention to abuse them. That doesn't happen with Axel. Axel was working with Roxas as part of his job for the Organization. He didn't intentionally seek Roxas out or deliberately manipulate him to like himself (Axel) more. Anyone shipping the relationship back in KH2 days would have considered it a workplace relationship that developed over time by happenstance. Axel didn't even have a heart to begin with to have feelings towards Roxas before they'd met.
Actually, I imagine the fact that Roxas is the impetus for Axel re-growing his heart is the reason the pairing was shipped so widely back when KH2 was released; Roxas ended up making Axel feel again and Axel didn't know that was possible. That would necessitate the ship be a slowburn, not love at first sight.
Axel really isn't that innocent on that behalf either. Your perspective works in the regular canon, but with AkuRoku being shipped as a romantic relationship, this means that gaining feelings for Roxas and vice-versa would have happened during work hours and the year they had spent together on the clock tower. Which is grooming in my opinion as it is during Roxas'
formative months. He's dependent on Axel for answers about activities, life, friendships, and love. This is an extrene imbalance of power. Unintentional at first, but AkuRoku has to be done with interest of romantic and sexual inclinations [eventually]. Otherwise it's not a ship. Even going by KHII standards, Roxas is half his size, is underaged, and Axel himself is portrayed as needy/clingy, perhaps due to Roxas making him "feel".
Honestly, I didn't need 358/2 Days to find it uncomfortable. It simply cemented it.
I'm not going to give people shit for shipping it, but it's not for me personally.
It isn’t about grooming in regards to these particular relationships with age discrepancies. I know they aren’t being groomed and that there isn’t a power discrepancy there. It’s strictly about the age gap and when the basis of their interactions began. Even though it was a brief meeting, Aqua would have perceived Riku as a child for 10 years until she saw him as a young teenager then finally properly met him as an older teen. Even though she’s known him longer as a teen, that doesn’t negate the fact that she knew him as a child while she was nearly an adult and considered him a child for a very long period of time.
Can't say much on that because it's complex, and I can't deem it unreasonable. I do think there's a difference between being attracted to the older version of him and not be attracted to the younger. And that's if Aqua has thought about Riku for years in the Realm of Darkness. I do believe her memory had to be jogged a bit to connect Kairi as that little girl she met once.