I think the Forsworn are threatening, it’s the series of events with Anduin and Genn that comes across as comical. And the whole thing starts off poorly with Bolvar whining and talking in completely nonsensical generically threatening language because if he actually said anything meaningful it would give away WTF Sylvanas is even doing or what the Jailor is up to but we aren’t even meant to know those things yet.
Overall it’s not a very well-constructed cinematic, so that’s 0 for 2 from the Blizz cinematic team after the N’zoth defeat cinematic letdown. I know they can do better than this, and probably will when the story of Shadowlands gets going properly. I hope they haven’t let the fawning sycophancy of content creators go to their heads.