I can't think of any perspective where he would be better off as a mind slave!
There is no evidence that he was anything other than what he chose to be. And unlike his sister, he was not being forced into a political marriage.
You are objecting to the reversal of traditional gender roles?
Your princess is in another castle.
I wouldn't even characterize it as a reversal of roles.
Even in the most cliche of old Disney movies, the princess/damsel was typically shown to have some semblance of competence and shown to have some manner of evolution into something better.
Aschenputtel maintains a household and is shown to be of a character which shines through her step-sisters' efforts; Ariel overcomes naivety to find confidence in herself and her own voice; etc; etc. There is some ability to overcome a challenge, bring something of value to their other half in "happily ever after," and/or an evolution into a better state.
In contrast, Airik gets barely any of that. All efforts to evolve from the boyish and indulgent f-boy prince saddled with low expectations into a competent man and partner end up going nowhere. He is "saved" by being put right back to where he started... in some ways worse than where he started.
To whom was he truly a "mind slave"?
The society which seeks to return him to a state of lesser value and lesser competence or the "evil" crone which intentionally sought him out because she saw value in him as something special and someone who had potential to be something greater?
Do I think the Crone was evil? Yeah, probably*, but I don't think it's necessarily that simple if looking at it from the perspective of Airik.
In a lot of ways, I imagine his journey home could be similar to when a lot of soldiers return home from combat and war. The country you leave isn't always the same one to which you come home.