How do you know that the thread is at the point where it will turn political?
Off the top of my head, I'd say when it drifts to discussions of things like "Our borders are just a thinly desguised screen door", it's hard to make a case that it's not.
To the extent that the thread drifts from the relationship between security and rail photography, and into the pure topic of security, I suppose you could say that the thread is off-topic. However, the pure topic of security is half the topic of the original post, so it does not seem unusual to bounce from one half the topic to the other during the discussion.
I suppose that I agree with you. If the subject was about marhmallows and trains, how far should the moderators let it go on, when it becomes all about marshmallows? I mean, it could turn back to trains, and away from marshmallows-right? ( In the past, some, although very few, threads have turned back away from politics, once they hit the slippery slope. I give kudos to those posters who have, in the past, pulled threads out of the fire.)
How do you know that the thread has steered completely away from railroads, and will never go back? History, I'm afraid. Which is not to say that a straying topic doesn't have interest, but this is a railroad forum.
You said this thread now has "political overtones." What are the political overtones in this thread? I'd say 2 things: the tone, and the use of buzzwords ...".Our borders are just a thinly desguised screen door"......"cartoon ineptness"...."72 virgins"...