Could a human use this bathroom if he identified as dog ?
Sure. Why not? The article says, "Guide and service dogs, emotional support animals and other pets traveling with passengers are all welcome to use the facilities."
Presumably that includes pet koalas and kangaroos. Just tell them you're a service animal.
“Could a human use this bathroom if he identified as dog?”
If Hillary barked, I’m sure they’d let her in. But that’s assuming that she’s a human. Very confusing.