Every drop in T+C's in each new base will lead to another drop in the next base. This is the way the pattern follows. It is slow and insidious until you find that your pay or T+C's is 25% or so less than another pilot in the same company out of another base. Then the company will seek to lower the original higher paid base.
That is not how it works, you are deliberately trying to paint a false picture to justify this stance. Airlines do this, companies do this. Do you think that a company like Intel for example will pay it's Californian workers the same as workers in Israel or elsewhere? Of course they don't and paying market salaries in one country does not effect the salaries paid in the higher cost jurisdiction. No company with a presence in multiple foreign markets will have one blanket set of T's and C;'s they will apply for everyone, that is absurd.
Your argument doesn't wash. The idea that somehow Belfast would lead to a lowering of T's and C's elsewhere is simply pie in the sky stuff. The general public (your customers) just cannot understand your stance on this. It is absurd.