Bringing in someone like Daniel Larson or Cobes early on would likely be a mistake IMO.
Their personalities, lore, fandoms, etc. are too “big” and would distract from the show itself. Instead of Fishtank it would become “It’s Cobes!!! Look at what Cobes is doing!!!” With these types of shows, the concept is more important than any single character (especially in the first season, where it’s important to prove the concept).
Imagine if on Survivor Season 1 you had 15 unknowns…and Charlie Sheen. That could be entertaining, but it would also become The Charlie Sheen Show.