I think you nailed it, really! I hadn't thought of making those connections, but it fits damn well. And what I like is that Zezé's faded form is just faint enough that you can't quite pick up his caprine features unless you're really looking hard.
There's something I'd add too in hindsight: One of the first chilling things Pedro experiences at the shed is himself, "P", involuntarily saying the words "It was you" in someone else's voice, then sensing his grandfather. Here's my additional theory:
- That voice saying those words was an echo of Pedro's grandfather
- It was in fact, Pedro's grandfather discovering Zezé's secret (likely after the massacre of the 12 tapirs) and catching him in the act
- Zezé is the one who killed Pedro's grandfather to silence him
- Zezé, knowing the powers of mythical peacocks, warns Pedro to leave not because "the hotel ain't real" but so he won't find him out