"on here" = site. The "off-topic" forum is for non-political & non-firearm related topics.
"political in nature" can encompass a number of different things and be somewhat gray at times. However, if you're talking about an elected official, government employee, law, policy, etc. - it should be related to guns. When the topic gets somewhat gray, moderators have discretion on when to step in.
The way I see it (and Joey may be able to articulate this better) is that 1) there are a number of people across the political spectrum who support gun rights & we're all here because of a shared interest in guns - trashing people's political/religious/etc. views distracts from our core reason for being here; and 2) it has been our experience that political discussions on here rarely turn out well.
If not discussed by us, who then. Were the ONLY ones who care!