Personally I think new management came and told them they will no longer be allowed to be friends with the EN girls like they used to because Holo want to farm Unicorns wallets.
Magni & Ves probably didn't like to hear that, and threatened to quit. so Holo silenced them and put them in streaming jail to rethink their actions. Holo wanted to stop any drama from brewing considering how dark of an outlook fans have about various drama concerning Nijisanji. Magni & Ves were probably given a harsh ultimatum, either come back and never mention/interact with the girls, or get graduated.
Here you can hear hard evidence that management blocks streamers from doing certain things just to appease fans and prevent any drama from brewing
https://www.youtube.com/watch?v=LAZkBMCor7oHolo management fears the ire of their crazy fans and loves their money simultaneously, so it's only logical they would do whatever the pay pigs want
If you don't like the fact of their disappearance, perhaps you should stop watching Holo EN alltogether because I guarantee you this behaviour will only continue happening.
