I feel like you have the pieces but in the wrong order. Colby putting on a halloween costume and then that line about Leon's father showed he knew he was out of his depth. Colby didn't perform because he knew he couldn't. Colby only has in his career Cardio. He wrestle spams and wears his opponents out. He shoots and chains TD after TD to force opponents to defend and get tired. He has never KO'd someone due to his striking skills. Has never subbed someone due to his submission skills. He knew he couldn't tire out Usman with TDs and knew the same for Leon. Once he realized he didn't get in his head he knew he was going to lose. Getting to decision was the victory, especially with getting on top for the last 2 min. Plays right into his Denial of reality character sadly.
I was truly hoping for a head kick KO.