Is the TV show Gotham on topic? In season 1, only one episode contains material that is seriously sci-fi in nature, which according to current guidelines only makes that episode on-topic, not the series. Or is it on-topic because batman makes all batman related works blanket on-topic?
TL;DR - Gotham should be on-topic because being in the "superhero" genre isn't judged purely by content, but by association.
Our Help Center doesn't, in fact, mention comic books or superheroes at all as part of our accepted topics. This is, I guess, because they're accepted as a sub-genre of SF or Fantasy (even though I believe they're a genre of their own). As such, it's a bit unclear where to draw the line between the heroic and the superheroic.
However, this vague line, as drawn, often puts the clearly heroic as on-topic, with Batman and the Arrow TV show (in its earlier seasons) seen as clearly on-topic despite having very few elements of super-science or unexplained phenomena. This is, I believe, because Batman and the Arrow are clearly in the "superhero comics" genre, not necessarily because of their actual content, but because of history and association - they share a history and stories with the clearly SFnal Superman, for instance.
This is why I believe Gotham should be on topic, just like other genre-free Batman stories or spin-offs. Because it's still Batman, in a variant of the Batman universe, which is accepted as on-topic here.
It's true that if you changed the names you'll just have a non-genre cop show, but the names are important. They're what draw a lot of viewers. They add a layer of meaning or people familiar with those names and their (alternate) history. It's a show watched by our site's members, because of its on-topic association.