This looks to be unintended, since a Fatshark employee did ask on stream through in-game text chat if Beastmen were in Twitch mode (too lazy to clip it from the latest VOD, I think it was a little after Martin was on stream).
Here’s a thread I wrote that you never read on how to improve Twitch mode. It’s full of suggestions, including gentle reminders to include Beastmen in Twitch mode because you forgot about it after release.
I’m also fairly certain that I posted a topic, or at least many repeated comments, in the feedback of the now closed Winds of Magic beta forum regarding this issue.
Thanks.