I think the Mike room was added because Mike was always meant to be a gag where the joke is that Tenna keeps calling out to this dude you never actually see, and Spamton mentioning Mike was to further drive in his connection to Tenna, and Chapter 2 being released standalone fucked up the pacing of the joke and made it seem like Mike was an important character Spamton was building up like Queen
So he made the Mike shit as a tribute to the fan content so people aren't completely disappointed by the lack of Mike