@Tryder I’m sure it has nothing to do with being selective in what is related content. That thread was almost entirely filled with equally off-topic drivel 
, your last post there was no worse than anything that had been posted there before.
The point where it “suddenly” was not allowed anymore was simply the point when it went on for too long. I’m pretty new to this forum, but from my experience on other forums, a little deviation is usually allowed and short off-topic conversations are fine. When it keeps going on for too long, the thread gets closed. It had nothing to do with the precise content of your post.
p.s. perhaps the next time you want to remain cool and cordial, try not to fan the flames with posts like this.