If the entire premise for their renewed relationship is supposed to be "it would be good for Ian" then no, thank you. Mina really doesn't deserve to be treated as nothing but a device for the fuckboi to have some sort of redemption arc after the shit he's put her through.
There are literal billions of other women out there Ian can hook up with, and he's working hard towards that goal already (and always has been)
I mean, I'm not discounting at all what Ian has done.
What he has done (intentionally trying to push Mina's buttons to see how far it takes till she breaks up with him) was him being a literal asshole and absolute deplorable thing to do.
Difference between then and now is that before, Ian wasn't aware (and didn't care about his actions), and now he does, given Edwin set him on the "self-reflect"/redemption path - assuming player chose this path for Ian.
Besides, let's set aside the "who Mina deserves" aspect, & looks at it down in terms of overall story aspect.
Can Ian hook up with billions of other women out there?
Sure. But establishing any as his potential girlfriend (as Edwin suggest just as Hell Week starts assuming player took "self-reflect" path with him) to enter the storyline?
Well, I don't see any.
Literally 99% of the women we saw Ian with have all been flings and never been in an actual relationship, so to establish someone new suddenly to establish as Ian's girlfriend in the future I just don't see working this far deep into the game (especially given I think this game is slowly heading closer towards its finishline).
Even character like Amber (girl who works at the hair salon, who did Edwin's new hair), was just given barely any characterization.
In contrast to that, following is what Mina has;
- was in a relationship with Ian previously (though not a good experience)
- already has much established characterization (hence no need to go into all the backstory of who she is and bla bla like with a new LI character for Ian)
- good friends with Edwin & Hana already (and decent relationship with the Carnations too, if her meet with them at Hana's concert is anything to go by)
additionally;
- with Mina, her story has always had a bit of an issue that it felt disjointed from the main storyline compared to other characters like Hana, Rose, Felicia, Veronica since she doesn't work at the club.
So having her forgive Ian, but they start off friends but gradually rekindle their romance I dunno about you but I can see working (compared to introducing a "nobody" LI for Ian whom I won't care about about at all at this stage).
By re-establishing the Mina-Ian romance, it solves a lot of issues in terms of introducing a new girlfriend for Ian (literally hitting 2 or even 3 birds with one stone lol).
Only thing which it comes down to is whether Mina decides to forgive Ian or not and start afresh for both of them.
Welcome to the morally high road, forgive and forget otherwise deal with it at the same level.
Uh, not really.
There doesn't just need to be the 2 extremes, but also the middle ground.
For instance, with taking the high road; sure.
Ian will likely give up on his vengeance plan (with Edwin's persuasion), but that doesn't mean he and MC can't go about ways in which they can make Grace feel really ...... defeated (for the lack of better term).
For instance, Ian's hobby is photography. Even Victoria states to Grace to possibly build that up as a job.
But Grace shows disdain/digust at even the mention of it. So what if Ian, becomes an actual photographer (as a legit job he takes seriously) and with help of MC gets some kind of leverage (like stated in this update) which stops Grace from cutting Ian off financially?
Grace failing in her scheme to send Ian to college and him getting the job she looks down upon (while unable to cut him off), I'd say is a good enough comeuppance for her (let's add Ian actually acting cold around her or even cutting off contact with her for good measure

).
Just because it's the high road route, it doesn't necessarily mean forgive and forget (and yes, I did use forgiveness for Ian and Mina example above, but difference between Ian and Grace is that Ian is completely different from Grace. Not to mention Grace's action not just impacted Ian, but also Victoria and Edwin, and Ian's actions towards Mina, despite being deplorable didn't affect other people causing them distress, tears & fury).
Doing so would just absolutely diminish the impact of Grace's Victoria blackmail & emotional effect it had on both Edwin & Ian.