>>90591596A - like pretty much the rest of the vtuber community, he put two and two together once Fauna put up the stream waiting room and half of the rest of Holo EN was sadposting, show-of-support-posting, and delaying or cancelling their own streams
B - Cover and Anycolor are business partners despite being rival companies, so technically the Holo and Niji vtubers are work colleagues to a limited extent; and regardless of that, because of the nature of their job, there is some leeway on the sort of insider information they can send to each other without violating NDA despite not being able to share that same information with the general public due to that same NDA
tldr stage performers have backstage access as part of the job, and have for as many dozens of centuries as stagecraft has been a thing
>>90591964He may be Niji, but he is probably not a sister. He's telling the sisters (including any sisters within his own company) to not hate on Holo just because they're not Niji, and to not hate on the Saplings just because Fauna is not Niji
He might get bonked by management for suggesting that there is no war between Niji and Holo in general, or between Niji EN and Holo EN in particular. He might not get bonked for that. But it's moot anyway, since there's an over 99.999% chance that he'll get culled at or very shortly after the merger.