Your forum, your rules but with a group of like minded individuals like TradGang, wouldn't it make sense to have a sub-forum for off-topic stuff like that? Seriously, some times its useful and beneficial to get the opinions of people you like and trust on topics that are only slightly related or maybe aren't related at all.
For instance, *years* ago, I started a thread about deer calls. Granted that thread could apply to topics other than trad archery, but many of us here hunt deer and deal with the complexities of getting deer "tradbow close". That topic can be useful and interesting to some of the folks around this campfire.
The others that you mentioned - I can see people here wanting to discuss those topics with each other. Why not - is there a big deal? If there were an off-topic sub forum for this sort of thing, people could chat, you could be bothered less from a policing perspective, and the other forums here could remain uncluttered.
What's the downside?