Ok, well let's take a look at the real issues here. First - if the forum users have interests in Chinese, Thai, or traditional uzbek cooking then so be it. It shouldn't be hard for anyone not interested in those areas to ignore them - heck you can even configure your profiles to ignore whole boards such as "anything other than curry" (which is where the Josephine thread is)
But.... If the non curry content is overwhelming in comparison to the BIR content then yes that should be considered a problem for a bir themed forum. BUT!!! Don't blame the Chinese chefs, etc for that. Ask why. more guys aren't documenting their curry cooking.
My opinion - this forum is excellent at retaining long term members who have seen it, done it, discussed it to death - they see no reason to keep on posting the BIR observations they were posting three years ago and they can cook just fine thank you. It's also good at attracting beginners who show up every day but rarely stuck around long. Where there is a gap is in the "middle-aged" demographic. Guys like MadrasAndy who have just aboutfigured things out and want to see nothing but BIR posts to help them fill in the gaps. It seems to drive these chaps crazy that the more experienced members' attention may have drifted.
This place is immeasurably more healthy than it was under George's inept reign. Leave it alone and it'll come good. I take my hat off to chewy tikka and jb and for sure there are many more who are cooking excellent Curries who could share their knowledge more, but that will come in time.