I follow a music-related channel on Youtube (ToolArchive, which posts concert videos, rare Tool stuff etc - literally hundreds of videos) that got pulled a few months ago. Guy who runs it reported basically the same scenario - no real reason given, just a blanket "violation of terms". The obvious reason speculated was that he'd violated copyright and someone from the band or the music publisher had initiated an action with YouTube which led to his channel getting yanked.
Turns out it was a mistake caused by a flagging algorithm they use, and he ended up getting the channel reinstated.

Not saying this is the case here, but it's one potential explanation.