It's fine. Because what we can deduce about the personality of the deceased from what we hear of him and the personality than we can see from his supposedly current self(because the author says so) are so different that they are basically different individual. You can just think of the other guy as someone that the seme of this story had a one-sided, kinda parasocial obsession with. The current guy doesn't make sense for the what we learn about the original person. He feels more like a relative that knew more things about his personal life than an average acquaintance would. And it's better to think of him that way. Dude having a one-sided attraction to a deceased person and a relative of said deceased person meet and bond over that shared link and grow attracted to each other. That's what this story actually is.
Sorry you missed out on the kind of eye candy you wanted. But, I think prefer it this way, where there is some sort of clean break between the original person and the new person when story demands that personality needs to completely switch gears instead of the many stories where a raging heterosexual suddenly goes full twink and we're expected to believe it all because the viewers wanna stare at two conventionally good looking men get it on with each other but also want the unnecessary drama brought about by the offensive and disrespectful trope that "I can fix your sexuality to fit my needs".
i mean yeah, they're different. but i guess i see no reason for them to be that different, considering the fact that it actually is the same dude lol. but what i meant was that the trope of effeminate drawn/depicted men who are either born naturals in taking it up the ass or straight up acted out as a girl with a dick in the yaoi genre (which has been going on since day one) is really boring to me. it's not really about the eye candy, but rather seeing a wider array of pairings. idk about you, but i really struggle finding stories here with a buff bottom that's not depicted as a big child or something. one would think this twink trope is rater offensive and disrespectful, no?
of course mc has to go from buff dude to skinny twink, which coincidentally also enjoys anal sex more than his old body (⌒▽⌒)