Side note, that was the biggest FU of the finale. Finn's dad not showing up for closure. Which would have been fine if they hadn't redeemed his character in the island arc. Should have left it at Finn realizing that people are who they are, instead of, no wait, he's actually a good guy for real.
martin
literally ascended out of existence theres
literally no way he could have come back
it didn't redeem his character either. it was his fault entirely that he had to abandon finn like that because he sold other people out earlier. he's always been a con-man- one moment in the past didnt make all of his actions suddenly okay, especially when he met up with finn again like a decade and a half later in a galactic prison. he used him to escape. he's a shitty person, he's not a good guy. you profoundly misunderstood that entire character if you thought islands redeemed him at all.
this is such a weird way of looking at martin's character honestly. it ignores his shitty actions in the present of the show and even in the past and just focuses on the one time he didnt act in self-interest. it made martin more a three dimensional character, yes, but it was still about him hurting others. hes a loving father in that moment, but it still didnt stop him from grifting finn in the future. he just kept burning bridges after that moment in time.
its more complicated than just him being a "good guy", especially when the only reason that moment happens at all is because he was being a piece of shit "bad guy".
i dont know how you can see it as a fuck you that he wasnt in the big finale to give finn "closure" when he was there in season 6's finale, giving finn the kind of closure that was much more in line with what he became, not who he was and that finn wouldn't find out about later on. he ascended from reality because finn rejected it and i think on some level, it was because he had become so separated from the ability to care about anyone but himself after that night. it hurt too much to even think about- to talk about- in that village with the little people when martin's ship crashed in ooo. martin's story ends in season 6, but that doesn't erase the damage he did in the past.
it just completely ignores the entire arc and focuses on a specific aspect to think it redeemed him at all.