I doubt there is any organisation that we might join where we would agree with 100% of the policies or actions of that organisation. Political parties are a prime example of this, we may agree with their stance on the economy but not on Europe, for example. So what do you do if you don't agree? Xollob decided he wanted to leave BALPA, good for him (apologies if you are a lady xollob) but others may decide to stay and try to effect change from within, good for them.
However, it is sad to see a "colleague" being such a coward; creating an Internet name and anonymously coming on a public forum to rant about BALPA, shame on you.