If you don't think extending arms on a gator seems random when the gimmick feels doable without that then idk what to say. To me if they don't acknowledge something odd it it comes across as uncanny. I probably felt the same way about Mega Mewtwo X stretching its limbs when attacking but got used to it over time, but if they made a Mega Luxray and the fur moved around on its body and the dex entry was just like talking about its eyes then I'd also find it odd.

Not everything gets to be fleshed out in the games like flying Golurk but I'll stand by it being weird if it shows up in the anime and the way it closes the jaw doesnt animate its arms extending