Dude, he's already butchered how many monsters in his home game?
That's all KR fuel right there.
If Frisk is still there during the Arisen's Genocide run, that might bring Chara back into the mix.
And then nobody would be able to play Dragon's Dogma again because their franchise would be dead.
The Pacifist route will end in him fighting either Omega Flowey or God Asriel, both of whom are hopeless boss-fights if he doesn't know to A. Call for help from the other souls, or B. Doesn't manage to save all the lost souls and keep Asriel comfortable.
The Genocide route only puts him up against Sans, whose time-warping isn't nearly as problematic. He still likely dies, but he at least has a fighting chance, if he really is FTL in his final forms.
Yeah, I'm not seeing him make it through either one, but Genocide is easier, seeing as the foe isn't freaking UNKILLABLE.
Seriously, Omega Flowey can just restart the fight whenever he wants until he wins, and God Asriel is literally a ten-year-old's DeviantArt Mary Sue character come to life, complete with rainbows, sparkles, an overly dramatic name, and attacks that are WAY too flashy and overkill.