>>14865597fun fact: Nobody stops you from watching Pomu, Rosemi and Enna right now, the way they are. Pomu already earns more in supas than most HoloENs and she prefers Nijisanji - she cringes at the thought of being seen as an idol after all. She's Pomu, she's no idol, she molests idols.
Rosemi is doing fine as well, has her peers around her and earns some good money.
Enna is still smol, but she just started, so yeah that doesn't mean much. Cover would have to take Millie as well though.
None of them have any reason to join Cover.