The fact he’s a human inside of an animal body changes things significantly over a person who would fuck a cat
The very notion is wrong and plainly silly. He's a FORMER human, who is now in fact a behemoth (that looks like a cat due to being that young). There's no such thing as "inside", besides his organs.
Though I recall a scene from "Star Wars - Return of the Jedi" where the human MC was indeed... inside of an animal.
Tama is is what he is. Namely a behemoth.
Who he is is who he is. His memories, preferences, and personality are the core of this.
What you are ≠ who you are.
Totally separate concepts.
Just as the former dragon is exactly that... a FORMER dragon. She remembers living a life as a dragon, but isn't one anymore.
Tama remembers living a life as a human, but isn't one anymore.
Aria wants to fuck what she believes is a cat. A very talented and loyal cat, but a cat all the same (in her mind). No way to paper over that. It's beastia... (ahem) "Inter-species Erotica".
But then again, what if Aria slept with Vulcan instead? That would also be "Inter-species Erotica", and I'd be here for it.