Can an adult love a child or children in general In a pure and platonic way? Absolutely, just look at teachers or people who adopt each other as siblings. Is that what's going on with OL-san? No, no it is not.
She may not be sexually attracted to Koharu or children in general, but her love is strongly romantic and therefore inappropriate. Sorry OL-san, just because you're not a lolicon in general doesn't mean you're not a lolicon for Koharu.