tbh I was really amazed that Michael brought the Fan to Worlds after I saw him use it at Nats. As for why he used it, I'm pretty sure it was because he wanted to use something along the lines of Zapdos, but it having a decent special attacking Flying type move and Will-O-Wisp.
Also the fact it practically won a match against Kyriakou, arguable one of the best VGC Players in the world is amazing. Nevertheless that he actually won two BO3 sets. As Level 51 said, going 2-4 in Worlds is a huge accomplishment just due to the fact that the best players in the world are there, for you to most probably play against. Also shoutout to the guys with me who helped start the Rotom-Fan chant <3