He didn't make a mistake its just that the last upper moons didn't have the will to fight anymore and douma fault for eating a demon slayer during battle when he should have went all out from the start
The amount of blatant disrespect that Tanjiro assa character recited is criminal my personal favorite anime character ever he’s rly like that PS: DKT IS HIM gaf what anyone talking abt💯💯
Shinobu: I don't like the idea of working with a demon Tamayo: and I don't like the idea of working with Demon Corps Ten minutes later Shinobu: GURL, U ARE INSANE! DID U MANAGE TO DO THIS KIND OF DRUG? Tamayo: YOU'RE ALSO NOT THAT BAD! AND TALENTED TOO! LET'S KICK MUZAN'ASS
Muzan never intended to fight the hashiras or demon slayers himself. He just wanted to let the uppermoons take care while he rest but tamayo and shinobu forced muzan to digest the poison which took time. And it was not a bad idea i mean the uppermoons only lost either they were not serious at all or just gave up.
Doma still beats akaza no diff even if akaza choose to eat women and would remain uppermoon3. Before those akaza bias comes after me, Akaza needs the person hes fighting with to have emotions. Doma doesnt show emotions.