On his part, he really does feel safer with someone else around... but he's also just being friendly. He has no reason to suspect her of anything -- and who knows, he might be able to show her that scientists aren't all bad.

"I'm a Professor of Pokeology. Specifically, I study the relationships between humans and Pokemon."

And he doesn't think to elaborate further -- after all, everyone knows what a Pokemon is, right? If he just thought about it a little deeper, though, the fact that she doesn't recognize a world-famous Pokemon researcher would tip him off that their surroundings aren't all that's odd here.