Typical BS is typically a response to typical ignorance. Typically speaking, after reading a few hundred of those kinds of threads it becomes obvious that the vast majority of those asking are only seeking approval on a minimum tank size, not an informed response based on actual hands on experience. A good reality check doesn't hurt anyone, and may result in saving some fish a (shortened) life full of stress. If that creates a barrier to entry, good.
Having said that personlly I would remove the festivum, chances are it won't hold up to the aggression as the rest of its tank mates mature. Ditto to the angel.