What made Decim think that Takashi was worthy of reincarnation in episode 1 anyway? He showed no signs of humanity, clearly hit the dart board intentionally several times, his jealousy is what got them killed and he tried to attack Machiko in the end. After episode 3 it's clear that he had the power to send them both to the void, so what the fuck made him think that Takashi wasn't a terrible person?
Don't think, just watch?
Think too much and you realize that if there is no steady creation of new souls, all souls go to the void eventually. So the bar is pointless. If there is a creation of new souls, why would you need reincarnation in the first place?
Takashi was terrible but was he shitty enough to merit eternal damnation, from Decim's point of view? Since he bought Machiko's painfully obvious lie he must have bought Takashi's about hitting the board by 'accident' and considered his breakdown at the end as an understandable reaction to being married to a total bitch.
Machiko did deserve reincarnation more than him though. Decim a shit.