I think the first line of the Realistic Likeness feat answers your question, whether it's considered "flavor" text or not. Humans only. If that's not enough, the feat specifically mentions when you are using your racial ability, which states that you can only take on a human form. There shouldn't be any table variation on this, unless the GM is not familiar with the racial ability or the feat. The abilities are cut and dry.
The problem is that the fluff text is just fluff. Sure, I agree it indicates the writers intent, but if abilities like Pageant of the Peacock were run based off clear intent instead of RaW, then fewer people would take it.
It's not honestly a huge drama, especially since one could combine it with other illusion magic or mundane disguises. It just seems odd that the ability is so... limited and underpowered.